Injection drive structure of injection pen and disposable injection pen

Abstract

This invention provides a disposable injection pen and its injection drive structure, including a screw that drives a pre-filled syringe to perform injection, and a drive sleeve that drives the screw to perform helical feeding. The screw has a non-circular cross-section on its outer circumferential surface. A non-circular through hole that mates with the screw is arranged inside the drive sleeve. The drive sleeve drives the screw to perform helical feeding through the engagement of the non-circular through hole with the outer circumferential surface of the screw. The screw rotates by being dragged by the drive sleeve. The screw's threads engage with a nut inside the injection pen, realizing helical feeding driven by the drive sleeve. The drive sleeve and the screw have a non-circular contact. When the drive sleeve rotates, it drives the screw to rotate synchronously. The non-circular cross-section contact enables torque transmission and axial guidance between the non-circular through hole and the outer circumferential surface of the screw, improving injection safety and stability.

Description

Technical Field

[0001] This invention relates to the field of injection pen technology, and more specifically, to an injection driving structure for an injection pen and a disposable injection pen. Background Technology

[0002] A disposable injection pen is a pen-shaped syringe pre-filled with medication, also known as a pre-filled injection pen. In one existing disposable automatic injection pen design, the pen contains a syringe assembly consisting of a pre-filled syringe, pre-filled liquid, and a rubber stopper.

[0003] When using the device, first remove the pen cap, which will bring out the pre-filled syringe needle cap. Then, press the protective shell to administer the subcutaneous injection. The injection is powered by a compression spring, torsion spring, or coil spring. The injection process is visible, as there is a viewing window near the needle on the protective shell. An injection completion beep will sound as the injection is nearing completion to remind the user. Stop pressing the protective shell; it will return to its pre-use position under the reaction force of the compression spring, locking in place. Pressing the protective shell again will prevent the needle tip from protruding, ensuring that the needle of the disposable auto-injector pen cannot extend after use and preventing puncture wounds.

[0004] In existing injection pen structures, the propulsion element is prone to misalignment during injection, easily impacting the sidewall of the pre-filled syringe and causing it to break. Simultaneously, the propulsion element experiences significant friction, resulting in uneven injection and affecting the injection stability of the pre-filled syringe. Summary of the Invention

[0005] In view of this, the present invention provides an injection drive structure for an injection pen and a disposable injection pen to ensure the stability of the injection pen during operation.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An injection drive structure for an injection pen includes a screw that pushes a pre-filled syringe to perform injection, and a drive sleeve that drives the screw to perform helical feeding.

[0008] The screw has a non-circular cross-section outer circumferential surface, and the drive sleeve is provided with a non-circular through hole that mates with the screw. The drive sleeve drives the screw to perform helical feeding through the mating of the non-circular through hole with the outer circumferential surface of the screw.

[0009] Preferably, in the above-mentioned injection drive structure of the injection pen, the screw has a threaded section with a cross-section that is racetrack-shaped with a double-arc rectangular structure;

[0010] The drive sleeve has a racetrack-shaped through hole, and the screw is driven by the through hole to perform helical feeding of the threaded section.

[0011] Preferably, in the above-mentioned injection drive structure of the injection pen, the drive sleeve includes a rotating sleeve and a drive cover that are inserted into each other along the axial direction. The rotating sleeve and the drive cover form a receiving cavity at the insertion position. The drive cover has a guide post extending into the receiving cavity, and the through hole is arranged in the guide post.

[0012] Preferably, in the above-described injection drive structure of the injection pen, the screw further has a cylindrical screw tail, and the screw is rotatably supported by its screw tail and arranged inside the rotating sleeve.

[0013] Preferably, in the above-described injection pen's injection drive structure, the screw further has a connecting head that abuts against the pre-filled syringe, and the connecting head has a spherical circular feature.

[0014] Preferably, in the above-described injection drive structure of the injection pen, the rotating sleeve includes a sleeve portion that inserts into the drive cover and a guide sleeve portion that extends coaxially with the sleeve portion; the guide sleeve portion is a cylindrical structure with a circular guide hole, and the tail of the screw is arranged inside the guide sleeve portion.

[0015] A disposable injection pen includes an upper pen shell assembly and a lower pen shell assembly that are assembled together. A pre-filled syringe is disposed inside the lower pen shell assembly, and a drive structure for driving the pre-filled syringe is disposed inside the upper pen shell assembly. The drive structure is an injection drive structure of the injection pen as described in any of the preceding claims.

[0016] Preferably, in the above-mentioned disposable injection pen, a fixed sleeve is installed on the upper pen shell, the driving sleeve is rotatably arranged inside the fixed sleeve, and a prestressed spring for dragging the driving sleeve to rotate is also arranged inside the fixed sleeve.

[0017] A locking slider is slidably arranged on the fixed sleeve to slide and limit the rotation of the driving sleeve.

[0018] Preferably, in the above-mentioned disposable injection pen, a nut is also arranged inside the upper pen shell assembly, and the threaded section of the screw and the threaded hole of the nut form a threaded transmission pair.

[0019] Preferably, in the above-mentioned disposable injection pen, the drive sleeve includes a rotating sleeve and a drive cover that are inserted into each other along the axial direction. The rotating sleeve and the drive cover form a receiving cavity at the insertion position. A sounding element that is driven to rotate by the screw when the injection is completed is also arranged in the receiving cavity. A compression spring that provides clamping stress is arranged in the receiving cavity.

[0020] The end of the screw is provided with a driving boss that drags the sound-producing element to perform axial displacement. Between the sound-producing element and the accommodating cavity, there is an impact boss that is driven by the compression spring to rotate and impact after the driving boss has been axially displaced.

[0021] The injection drive structure of the injection pen provided by this invention includes a screw that pushes a pre-filled syringe to perform injection, and a drive sleeve that drives the screw to perform helical feeding. The screw has a non-circular cross-section outer circumferential surface, and a non-circular through hole that mates with the screw is arranged inside the drive sleeve. The drive sleeve drives the screw to perform helical feeding through the non-circular through hole and the engagement of the screw's outer circumferential surface. The screw rotates by being dragged by the drive sleeve, and the screw's threads engage with a nut inside the injection pen, realizing helical feeding driven by the drive sleeve. The drive sleeve and the screw have a non-circular contact. When the drive sleeve rotates, it drives the screw to rotate synchronously. The non-circular cross-section contact enables torque transmission and axial guidance between the non-circular through hole and the screw's outer circumferential surface. Compared with the existing structure that sets a nut on the drive sleeve, the cross-sectional fit between the screw and the drive sleeve is higher and the transmission rigidity is better. By changing the original helical feeding structure between the screw and the drive sleeve from the original threaded nut to a structure where the drive sleeve only provides rotational force to the screw, the screw obtains more stable axial support, the screw's centering is better guaranteed, and the injection push between the screw and the pre-filled syringe can further achieve axial guiding support, reducing the risk of tilting of the pre-filled syringe during injection and improving injection safety and stability. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 An exploded view of the first structure of the disposable injection pen provided in this application;

[0024] Figure 2 A cross-sectional view of the assembly structure of the disposable injection pen provided in this application;

[0025] Figure 3 for Figure 1 A schematic diagram of the internal structure of a locking slider;

[0026] Figure 4 for Figure 1 Schematic diagram of the internal structure of the drive cover;

[0027] Figure 5 A schematic diagram of the groove structure of the drive cover;

[0028] Figure 6 for Figure 1 Schematic diagram of the rotating sleeve;

[0029] Figure 7 This is a schematic diagram of the second direction structure of the rotating sleeve;

[0030] Figure 8 for Figure 1 Schematic diagram of the middle screw;

[0031] Figure 9 for Figure 1 Schematic diagram of the middle nut structure;

[0032] Figure 10 This is a schematic diagram of the second-direction structure of the nut;

[0033] Figure 11 for Figure 1 Schematic diagram of the middle gasket structure;

[0034] Figure 12 for Figure 1 A schematic diagram of the bottom structure of the central drive cover;

[0035] Figure 13 for Figure 1 A schematic diagram of the internal structure of the upper and middle part of the pen casing;

[0036] Figure 14 This is a schematic diagram of the insertion part of the upper pen shell;

[0037] Figure 15 for Figure 1 Schematic diagram of the center positioning structure of the drive cover;

[0038] Figure 16 for Figure 1 Schematic diagram of the structure of the lower and middle pen casing;

[0039] Figure 17 This is a schematic diagram of a pre-filled syringe. Detailed Implementation

[0040] This invention discloses a disposable injection pen that ensures stability during the operation of the injection pen.

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] like Figures 1-5As shown, Figure 1 An exploded view of the first structure of the disposable injection pen provided in this application; Figure 2 A cross-sectional view of the assembly structure of the disposable injection pen provided in this application; Figure 3 for Figure 1 A schematic diagram of the internal structure of a locking slider; Figure 4 for Figure 1 Schematic diagram of the internal structure of the drive cover; Figure 5 A schematic diagram of the groove structure of the drive cover; Figure 6 for Figure 1 Schematic diagram of the rotating sleeve; Figure 7 This is a schematic diagram of the second direction structure of the rotating sleeve.

[0043] This application provides a disposable injection pen, and an injection pen driving structure inside the disposable injection pen.

[0044] The injection pen's injection drive structure includes a screw 019 that pushes a pre-filled syringe 005 to perform injection, and a drive sleeve that drives the screw 019 for helical feeding. The screw 019 has a non-circular cross-section outer circumferential surface. A non-circular through hole 024 that mates with the screw is arranged inside the drive sleeve. The drive sleeve drives the screw 019 for helical feeding through the engagement of the non-circular through hole 024 with the outer circumferential surface of the screw 019. The screw 019 rotates by being dragged by the drive sleeve. The screw 019's threads engage with a nut inside the injection pen, realizing helical feeding driven by the drive sleeve. The drive sleeve and the screw 019 have a non-circular contact. When the drive sleeve rotates, it drives the screw 019 to rotate synchronously. The non-circular cross-section contact enables torque transmission and axial guidance between the non-circular through hole 024 and the outer circumferential surface of the screw 019. Compared with the existing structure that sets a nut on the drive sleeve, the cross-sectional fit between the screw 019 and the drive sleeve is higher and the transmission rigidity is better. By changing the original helical feeding structure between the screw 019 and the drive sleeve from the threaded nut to a structure where the drive sleeve only provides rotational drive to the screw, the screw 019 obtains more stable axial support, the centering of the screw 019 is better guaranteed, and the injection push between the screw 019 and the pre-filled syringe 005 can further achieve axial guiding support, reducing the risk of tilting of the pre-filled syringe during injection and improving injection safety and stability.

[0045] The rotating sleeve 017 and the drive cover 014 together constitute the drive sleeve that drives the screw 019 to rotate. Multiple drive components that drag the drive sleeve to rotate are installed inside the disposable injection pen.

[0046] Specifically, the disposable injection pen includes an upper pen shell assembly and a lower pen shell assembly that are assembled together. The lower pen shell assembly includes a pen cap 001 and a protective shell 002 that is fitted inside the pen cap 001. An injection bracket 004 that supports a pre-filled syringe 005 is arranged in the inner ring of the protective shell 002. The pen cap 001 is provided with a claw extending towards the bracket, which presses against the axial edge of the needle cap of the pre-filled syringe 005. The lower pen shell assembly supports the injection bracket 004 by the protective shell 002 installed inside the pen cap 001. The pre-filled syringe 005 can be fixed inside the injection bracket 004. The claw inside the pen cap 001 presses against the axial edge of the needle cap. By using the claw to hold the needle cap against the circumferential edge, the needle cap is subjected to an axial pull-out force. The holding structure is stable, ensuring that the needle cap can be easily pulled out.

[0047] The upper pen housing assembly is the driving part that actuates the pre-filled syringe 005 to perform the injection action. It includes an upper pen housing 008 and a driving structure disposed within the upper pen housing 008. The upper pen housing 008 and the lower pen housing 003 are inserted into each other, and the end of the upper pen housing 008 is sealed and protected by a rear cover 013.

[0048] Specifically, this embodiment achieves the injection driving function through 11 parts, including protective shell 002, locking slider 009, rotating slider 010, torsion spring 011, fixing sleeve 012, rotating sleeve 017, sound spring 015, drive cover 014, nut 007, screw 019, and washer 006.

[0049] Press the protective shell 002, and the protective shell 002 slides upward toward the pen shell 008. The protective shell 002 abuts against the locking slider 009, pushing the locking slider 009 to slide synchronously. The locking slider 009 abuts against the rotating slider 010 in the axial direction, thereby pushing the rotating slider 010 to slide.

[0050] Locking slider 009 and rotating slider 010 are fitted onto the outer periphery of fixed sleeve 012. A guide groove is provided on the outer periphery of fixed sleeve 012, and a guide boss is provided on the inner ring of rotating slider 010 to abut against the groove on fixed sleeve 012. A torsion spring 011 is also fitted between rotating slider 010 and fixed sleeve 012. Correspondingly, the guide groove includes a vertical groove and a horizontal groove formed on the outer periphery of fixed sleeve 012. The vertical groove serves as an axial sliding guide, and the horizontal groove serves as a guide for rotating slider 010 to rotate circumferentially after sliding to a predetermined position, due to the torsional force accumulated by the torsion spring 011. A collision wall is provided at the bottom of the horizontal groove to collide with the guide boss. The collision between the guide boss and the collision wall produces a sound, serving as an audible indication that the protective shell 002 has axially slid into place.

[0051] The locking slider 009 and the rotating slider 010 are axially abutted together, and both can rotate freely. During the pressing process, the protective shell 002 first abuts against the shaft end of the locking slider 009, and then the locking slider 009 sequentially abuts against the shaft end of the rotating slider 010. As the protective shell 002, the locking slider 009, and the rotating slider 010 slide synchronously, the locking relationship between the locking slider 009 and the drive cover 014 is gradually released. When the rotating slider 010 moves from the vertical slide groove into the horizontal slide groove, the torsion spring 011 is compressed. After a certain displacement, a sliding completion indicator sound is emitted, and the locking relationship between the locking slider 009 and the drive cover 014 is simultaneously released. The drive cover 014 then enters an automatic rotation state, and the injection stage begins.

[0052] Specifically, the inner wall surface of the locking slider 009 is provided with internal protrusions 020. The locking slider 009 is an annular sleeve structure, and the internal protrusions 020 are strip-shaped bosses arranged on the inner wall surface of the locking slider 009. Correspondingly, the outer wall surface of the drive cover 014 is provided with external protrusions 021. During the axial sliding of the locking slider 009, the external protrusions 021 maintain abutting contact with the internal protrusions 020 in the circumferential direction. Due to the strip-shaped boss structure of the internal protrusions 020, the external protrusions 021 maintain abutting contact with the internal protrusions 020 as the locking slider 009 slides. When the external protrusions 021 slide to the end of the internal protrusions 020, the two separate. At this time, the locking slider 009 disengages from the drive cover 014, and the internal protrusions 020 are released from their constraint on the external protrusions 021.

[0053] The drive cover 014 is coaxially connected to the rotating sleeve 017. The drive cover 014 is a cylindrical structure. It is locked and positioned with the locking slider 009 through the external protrusion 021 on the outer wall surface, and enters a free rotation state after being unlocked from the locking slider 009.

[0054] The rotating sleeve 017 includes a sleeve portion 0171 that is inserted into the drive cover 014 and a guide sleeve portion 0172 that extends coaxially with the sleeve portion 0171. A screw 019 is arranged inside the rotating sleeve 017. The screw 019 is driven to rotate by the drive cover 014 through the sleeve portion 0171 and the rotational feed of the screw 019 is guided by the guide sleeve portion 0172. The sleeve portion 0171 of the rotating sleeve 017 is inserted into the inner ring of the drive cover 014. The drive cover 014 is arranged on the shaft end of the fixed sleeve 012. A torsion spring 018 is fixedly arranged on the inner ring of the fixed sleeve 012. The first end of the torsion spring 018 is fixed to the root of the fixed sleeve 012, and the second end is fixed to the sleeve portion 0171. The torsion spring 018 is pre-applied with torque. After the drive cover 014 is unlocked and released, the torque stored in the torsion spring 018 drives the drive cover 014 and the rotating sleeve 017 to rotate together, thereby driving the screw 019 to feed. Specifically, the inner ring of the drive cover 014 has a groove 022 extending through its wall thickness. Correspondingly, the outer ring of the rotating sleeve 017 has protruding protrusions 023. During the insertion of the rotating sleeve 017 into the inner ring of the drive cover, the protrusions 023 abut against the inner wall surface of the rotating sleeve 017 and fall into the groove 022 as the insertion depth increases. The protrusions 023 fall into the groove 022, thus achieving a fixed connection between the drive cover 014 and the rotating sleeve 017. Preferably, the groove 022 includes a pair arranged radially along the drive cover 014, and correspondingly, the protrusions 023 include a pair arranged radially along the rotating sleeve 017, thereby achieving a stable connection between the two.

[0055] Under the counter-rotating force of the torsion spring 018, the rotating sleeve 017 begins to rotate, further driving the drive cover 014 to rotate. The non-circular through hole 024 inside the drive cover 014 matches the shape feature 025 of the screw 019, thereby driving the screw 019 to rotate. The drive cover 014 also contains a sounding element 016 and a sounding spring 015, which are triggered during the feeding process of the screw 019 to emit an injection prompt sound, indicating that the injection stage has begun.

[0056] like Figures 8-16 As shown, Figure 8 Figure 1 Schematic diagram of the middle screw; Figure 9 for Figure 1 Schematic diagram of the middle nut structure; Figure 10 This is a schematic diagram of the second-direction structure of the nut; Figure 11 for Figure 1 Schematic diagram of the middle gasket structure; Figure 12 for Figure 1 A schematic diagram of the bottom structure of the central drive cover; Figure 13 for Figure 1 A schematic diagram of the internal structure of the upper and middle part of the pen casing; Figure 14 This is a schematic diagram of the insertion part of the upper pen shell; Figure 15 for Figure 1Schematic diagram of the center positioning structure of the drive cover; Figure 16 for Figure 1 Schematic diagram of the structure of the lower and middle pen casing; Figure 17 This is a schematic diagram of a pre-filled syringe.

[0057] Specifically, in this embodiment, the rotation of the rotating sleeve 017 drives the screw 019 to rotate accordingly.

[0058] The rotating sleeve 017 and the drive cover 014 are assembled into a single structure. The rotation of the rotating sleeve 017 drives the screw 019 to follow. At the same time, the screw 019 needs to be axially fed during rotation so that it can push the pre-filled syringe 005 to perform the injection action.

[0059] During rotation, the screw 019 needs to be ensured to move only in the axial direction to avoid tipping over and causing jamming with the pre-filled syringe 005, which would affect injection. The axial feed of the screw 019 is achieved through the upper pen housing 008, the fixed sleeve 012, the rotating sleeve 017, and the drive cover 014; while the axial guiding function of the screw 019 to ensure positive orientation and prevent tilting is achieved by the nut 007 installed on the upper pen housing 008.

[0060] With the threaded section 026 of the screw 019 engaging with the threaded hole 027 of the nut 007, the screw 019 rotates forward. The circular feature 028 of the screw 019 engages with the through hole 029 of the washer 006, and the screw 019 then pushes the washer 006 forward to complete the injection.

[0061] Specifically, the rotating sleeve 017 begins to rotate under the reversing force of the torsion spring 018, which further drives the drive cover 014 to rotate. The non-circular through hole 024 inside the drive cover 014 matches the shape feature 025 of the screw 019, thereby driving the drive cover 014 to drive the screw 019 to rotate.

[0062] The screw 019's external features 025 include a connecting head that abuts against the pre-filled syringe 005. The connecting head has a spherical circular feature 028. A gasket 006 is provided on the pre-filled syringe 005. The gasket 006 has a through hole 029. The circular feature 028 is inserted into the through hole 029 to drive the injection of the pre-filled syringe 005 through the gasket 006. The main body of the screw 019 is a threaded section 026, which consists of an arc surface structure and a straight section structure. From the cross-section of the screw 019, its cross-section is a racetrack shape with a rectangular structure with double arc edges. The thread of the screw 019 is opened on the double arc edge structure, so that the screw 019 can utilize its double arc surface structure and straight section external features 025 to simultaneously achieve follow-up rotation and axial feed with the rotating sleeve 017. The screw 019 also has a cylindrical screw tail.

[0063] Of course, the non-circular structural features of the screw 019 can also adopt elliptical, polygonal, or irregular cross-sectional structures. Correspondingly, the non-circular through hole 024 has a cross-sectional shape that matches the screw 019, so that the screw 019 and the non-circular through hole 024 can rotate synchronously and slide relative to each other axially, thus providing axial guidance for the screw 019.

[0064] Furthermore, the guide sleeve 0172 of the rotating sleeve 017 has a cylindrical structure with a circular guide hole. By utilizing the guide sleeve 0172 and the cylindrical screw tail, the feed guidance of the screw 019 can be realized during the feeding process, avoiding feed deviation problems such as tilting of the screw 019.

[0065] The inner ring of the drive cover 014 has a non-circular through hole 024. The inner hole of the non-circular through hole 024 is also a racetrack-shaped structure. The threaded section 026 of the screw 019 is clearance-fitted with the non-circular through hole 024. During the rotation of the drive cover 014, the non-circular through hole 024 drives the threaded section 026 to rotate synchronously, thereby making the entire screw 019 and the drive cover 014 rotate synchronously.

[0066] The rotation of the drive cover 014 causes the screw 019 to rotate accordingly. The axial feed of the screw 019 is provided by the nut 007 fixed on the upper pen shell 008.

[0067] Specifically, the upper pen shell 008 and the lower pen shell 003 are inserted into each other at the shaft end. The end of the upper pen shell 008 has an insertion part 0081, and the end of the lower pen shell 003 has a receiving cavity 0091. The outer periphery of the insertion part 0081 has an outward protruding locking point 0082, and the inner ring of the receiving cavity 0091 has an inwardly recessed locking groove 0092 that engages with the outwardly protruding locking point 0082. The two are connected by insertion through the insertion part 0081 and the receiving cavity 0091, and the outwardly protruding locking point 0082 falls into the inwardly recessed locking groove 0092, thus locking into place and completing the connection between the upper pen shell 008 and the lower pen shell 003.

[0068] The drive cover 014 has two axial ends, one open for insertion into the rotating sleeve 017, and the other closed. A hollow cylinder 0141 is nested inside the closed end, forming an annular cavity between the hollow cylinder 0141 and the drive cover 014. The hollow cylinder 0141 and the drive cover 014 are coaxially arranged, and the inner hole of the hollow cylinder 0141 is a non-circular through hole 024. The structural design of the hollow cylinder 0141 allows for a certain length of rigid contact with the screw 019, ensuring the stability of the rotating support structure. Simultaneously, the annular cavity structure between the hollow cylinder 0141 and the drive cover 014 provides axial sliding space for the sound-emitting component 016.

[0069] A first annular boss 0142 extends coaxially from the closed end of the drive cover 014, and an annular step structure is formed between the first annular boss 0142 and the closed end of the drive cover 014.

[0070] Furthermore, the inner ring of the insertion part 0081 is also provided with a nut 007. The nut 007 includes a central nut 038 with a cylindrical center. A mounting bracket extends from the outer periphery of the central nut 038, and a mounting protrusion 036 extends from the outer periphery of the mounting bracket. The inner ring of the insertion part 0081 is provided with a mounting groove 037 recessed along the wall thickness direction. The nut 007 is inserted into the insertion part 0081 axially and is engaged and limited within the mounting groove 037 by the mounting protrusion 036, thereby achieving a fixed connection between the nut 007 and the upper pen shell 008.

[0071] The center nut 038 has a threaded hole 027 at its center. The threaded section 026 of the screw 019 and the threaded hole 027 of the nut 007 form a threaded transmission pair. When the screw 019 is driven to rotate around its central axis, the nut 007 is limited and fixed in the circumferential and axial directions. The threaded transmission pair converts the rotational motion of the screw 019 into a linear feed motion along the central axis, thereby realizing the axial displacement of the screw 019 relative to the nut 007.

[0072] With the threaded section 026 of the screw 019 engaging with the threaded hole 027 of the nut 007, the screw 019 rotates forward. The circular feature 028 of the screw 019 engages with the through hole 029 of the washer 006, and the screw 019 further pushes the washer 006 of the pre-filled syringe 005 forward to complete the injection.

[0073] This embodiment uses four parts—upper pen shell 008, fixed sleeve 012, rotating sleeve 017, and drive cover 014—to maintain the alignment of nut 007 and screw 019 during the injection process.

[0074] Both the upper pen shell 008 and the drive cover 014 have a cylindrical structure. The outer circle 030 of the internal through hole of the upper pen shell 008 is aligned with the cylindrical feature 031 of the drive cover 014.

[0075] The rotating sleeve 017 is aligned by the tail end 032 of its guide sleeve 0172 engaging with the internal through hole 033 of the fixed sleeve 012;

[0076] The upper pen shell 008 and the fixing sleeve 012 are fixedly connected by the groove 034 of the upper pen shell 008 and the protrusion 035 of the fixing sleeve 012.

[0077] Nut 007 and upper pen shell 008 are fixedly engaged by mounting protrusion 036 of nut 007 and mounting groove 037 of upper pen shell 008. Nut 007 and upper pen shell 008 are aligned by the central nut 038 of the cylindrical feature of nut 007 and the inner circle 039 of the internal through hole of upper pen shell 008. With upper pen shell 008 as the guiding reference, the screw 019 and nut 007 are guided during the injection process, and the injection is kept stable.

[0078] The above description of the disclosed embodiments enables those skilled in the art to make or use the 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 invention. Therefore, the 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. An injection driving structure for an injection pen, characterized in that, Includes a screw that pushes the pre-filled syringe to perform injection, and a drive sleeve that drives the screw to perform helical feeding; The screw has a non-circular cross-section outer circumferential surface, and the drive sleeve is provided with a non-circular through hole that mates with the screw. The drive sleeve drives the screw to perform helical feeding through the mating of the non-circular through hole with the outer circumferential surface of the screw.

2. The injection driving structure of the injection pen according to claim 1, characterized in that, The screw has a threaded section with a cross-section that is racetrack-shaped with a double-arc rectangular structure; The drive sleeve has a racetrack-shaped through hole, and the screw is driven by the through hole to perform helical feeding of the threaded section.

3. The injection driving structure of the injection pen according to claim 2, characterized in that, The drive sleeve includes a rotating sleeve and a drive cover that are inserted into each other along the axial direction. The rotating sleeve and the drive cover form a receiving cavity at the insertion position. The drive cover has a guide post extending into the receiving cavity, and the through hole is arranged in the guide post.

4. The injection driving structure of the injection pen according to claim 3, characterized in that, The screw also has a cylindrical screw tail, which is rotatably supported by the screw tail and arranged inside the rotating sleeve.

5. The injection driving structure of the injection pen according to claim 4, characterized in that, The screw also has a connecting head that abuts against the pre-filled syringe, the connecting head having a spherical circular feature.

6. The injection driving structure of the injection pen according to claim 5, characterized in that, The rotating sleeve includes a sleeve portion that inserts into the drive cover and a guide sleeve portion that extends coaxially with the sleeve portion; the guide sleeve portion is a cylindrical structure with a circular guide hole, and the tail of the screw is arranged inside the guide sleeve portion.

7. A disposable injection pen, characterized in that, The device includes an upper pen shell assembly and a lower pen shell assembly that are assembled and fitted together. A pre-filled syringe is disposed inside the lower pen shell assembly, and a drive structure for driving the pre-filled syringe is disposed inside the upper pen shell assembly. The drive structure is the injection drive structure of the injection pen as described in any one of claims 1-6.

8. The disposable injection pen according to claim 7, characterized in that, A fixed sleeve is installed on the upper pen shell, and a drive sleeve is rotatably arranged inside the fixed sleeve. A prestressed spring for dragging the drive sleeve to rotate is also arranged inside the fixed sleeve. A locking slider is slidably arranged on the fixed sleeve to slide and limit the rotation of the driving sleeve.

9. The disposable injection pen according to claim 8, characterized in that, The upper pen shell assembly also contains a nut, and the threaded section of the screw and the threaded hole of the nut form a threaded transmission pair.

10. The disposable injection pen according to claim 9, characterized in that, The drive sleeve includes a rotating sleeve and a drive cover that are inserted into each other along the axial direction. The rotating sleeve and the drive cover form a receiving cavity at the insertion position. A sounding element that is driven to rotate by the screw when the injection is completed is also arranged in the receiving cavity. A compression spring that provides clamping stress is arranged in the receiving cavity. The end of the screw is provided with a driving boss that drags the sound-producing element to perform axial displacement. Between the sound-producing element and the accommodating cavity, there is an impact boss that is driven by the compression spring to rotate and impact after the driving boss has been axially displaced.

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