A multi-dose adjustable prefilled injection pen

Abstract

The present invention discloses a multi-dose adjustable prefilled injection pen, comprising a pen body, an injection push rod, a push rod sleeve, a clutch hub, an end stopper, and a dose hub. The injection push rod is threadedly connected to the pen body, the push rod sleeve slides with the injection push rod in the injection direction and can transmit torque in the injection push rod's screwing direction. The push rod sleeve is connected to the pen body via a first set of ratchet and pawl mechanisms, the clutch hub slides with the push rod sleeve in the injection direction, the dose hub is rotationally connected to the pen body via a thread, and the clutch hub and the dose hub are restricted from rotation by a disengageable clamping structure in the injection direction. The end stopper and the dose hub are supported by support legs that can elastically deform in the injection direction. Rotating the dose hub before the support legs elastically deform can disengage the clamping structure. This invention can effectively solve the problems of inconvenient operation and poor dose adjustment effect of current injection pens.

Description

Technical Field

[0001] The present invention relates to the technical field of injection equipment, and more particularly to a multi-dose adjustable prefilled injection pen. Background Art

[0002] Current injection pen products have complex structures, a large number of parts, and multiple processing steps, resulting in low product reliability; some products use gluing to bond parts together during processing, which poses biological risks; product parts involve many metal products, resulting in increased product costs and poor performance.

[0003] In summary, how to effectively solve the problems of inconvenient operation and poor dosage adjustment effect of current injection pens is an urgent problem that those skilled in the art need to solve. Summary of the Invention

[0004] In view of this, an object of the present invention is to provide a multi-dose adjustable prefilled injection pen, which can effectively solve the problems of inconvenient operation and poor dose adjustment effect of current injection pens.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A multi-dose adjustable prefilled injection pen comprises a pen body, an injection push rod, a push rod sleeve, a clutch hub, an end stopper, and a dose hub. The injection push rod is connected to the pen body via a threaded connection whose axis extends in the injection direction. The push rod sleeve slides with the injection push rod in the injection direction and can transmit torque in the injection push rod's screwing direction. The push rod sleeve and the pen body are connected via a first set of ratchet and pawl mechanisms to prevent the push rod sleeve from rotating relative to the pen body in the direction of retraction of the injection push rod. The clutch hub slides with the push rod sleeve in the injection direction and limits relative rotation. The dose wheel hub is rotatably connected to the pen body via a thread and can be pushed forward when the dose wheel hub is axially driven. The clutch hub and the dose wheel hub are restricted from rotating by a clamping structure that can be disengaged along the injection direction. The end limiter and the dose wheel hub are supported by a supporting foot that can elastically deform along the injection direction. When the end limiter is subjected to a thrust in the injection direction to elastically deform the supporting foot, the clamping structure can be prevented from being disengaged. Moreover, rotating the dose wheel hub before the supporting foot is elastically deformed can push the clamping structure to be disengaged.

[0007] When using this multi-dose adjustable prefilled injection pen, the cartridge is secured to the pen body, and the injection push rod is positioned against the cartridge's rubber stopper. The dose wheel hub is now in its initial position relative to the pen body. The end stopper is then pushed in the injection direction, causing the support leg to elastically deform and thereby preventing the engaging structure from disengaging. The end stopper then transmits the injection-direction thrust to the dose wheel hub, causing it to rotate forward. Because the engaging structure is now engaged, the dose wheel hub drives the clutch hub to rotate, which in turn drives the push rod sleeve and the injection push rod to initiate the injection. After the first injection is completed, the end stopper is released, causing it to reposition. The dose wheel hub then returns to its initial position, facilitating dose adjustment for the next injection. To adjust the dose again, the dose wheel hub can be rotated relative to the pen body. During this rotational process, the dose wheel hub, unrestricted by the end stopper, cannot rotate the clutch hub, but instead causes the clutch hub to slide in the opposite direction of the injection direction. During this rotational process, the injection push rod and push rod sleeve remain stationary relative to the pen body. When the dose needs to be adjusted and reduced, the dose wheel hub needs to be screwed in. Since the end limiter is not subjected to the force in the injection direction, the clutch wheel hub will not rotate. In this multi-dose adjustable prefilled injection pen, an end limiter is provided, which controls the rotational connection between the dose wheel hub and the clutch wheel hub through an elastic support foot. Therefore, when injecting, the injection can be completed by directly pressing the end limiter. When rotating to adjust the dose, it is only necessary to rotate the dose wheel hub alone, making the operation very convenient and simple. The dose adjustment operation is simple, and the overall structure is very simple, with few parts and easy assembly. There is no need to use metal springs and other structures, which makes the overall cost lower. In summary, this multi-dose adjustable prefilled injection pen can effectively solve the problems of inconvenient operation and poor dose adjustment effect of current injection pens.

[0008] Preferably, a dose limiting nut is further included, which is threadedly connected to the clutch hub and slides with the dose hub along the injection direction and limits relative rotation, so that when the dose hub rotates relative to the clutch hub, the dose limiting nut moves along the axial direction of the clutch hub.

[0009] Preferably, the tip of the supporting foot is a pawl, and the end of the dosage hub has a ratchet that cooperates with the pawl on the supporting foot to prevent relative rotation in the screwing direction; the end limiter has a limiting flange, and the dosage hub is correspondingly provided with a limiting groove surrounding the limiting flange to limit the range of movement of the limiting flange in the injection direction.

[0010] Preferably, the clutch hub has a cam at the rear end, the cam has a plurality of circumferentially evenly distributed arc-shaped protrusions on the front side, the dosage hub has an annular shoulder inside the rear end, and the annular shoulder has an arc-shaped tooth groove distributed circumferentially and matched with the arc-shaped protrusions on the rear side; the rear end of the clutch hub is connected to the end limiter by a second set of ratchet and pawl mechanisms.

[0011] Preferably, it also includes an end button, which is clamped on the end limit piece around the end button and has a force transmission cylinder extending along the injection direction in the middle. The front end of the force transmission cylinder is against the end limit piece and is spherical.

[0012] Preferably, the pen body comprises a barrel and a push rod nut inserted into the barrel, the push rod nut is threadedly connected to the injection push rod, and is connected to the push rod sleeve via the first set of ratchet and pawl mechanisms.

[0013] Preferably, the injection push rod, the push rod sleeve, the clutch hub, the dose limiting nut, the dose hub and the body are sequentially arranged.

[0014] Preferably, a window is provided on the pen body, and a spirally distributed scale is provided on the outer side of the dose wheel hub so that the scale can pass through the window in sequence when the dose wheel hub is screwed in.

[0015] Preferably, it also includes a medicine bottle rack clamped on the front end of the barrel, the rear end of the medicine bottle rack has a medicine bottle ring, the front end of the medicine bottle ring is used to abut against the medicine bottle in the medicine bottle rack, and the rear end is used to abut against the pen body, the front end of the injection push rod has a push rod knob that can be rotated to abut against the medicine bottle stopper, and the front end of the medicine bottle rack has a threaded column for connecting the needle.

[0016] Preferably, it also includes a pen cover, and the rear end of the pen cover is snap-connected with the medicine bottle holder. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic cross-sectional view of a multi-dose adjustable prefilled injection pen provided in an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of the explosion structure of a multi-dose adjustable prefilled injection pen provided by an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of the external structure of the multi-dose adjustable prefilled injection pen with the pen cap removed provided by an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of the structure of the multi-dose adjustable prefilled injection pen provided by an embodiment of the present invention with the dose hub rotated out;

[0022] Figure 5 A schematic cross-sectional view of the dosage hub of a multi-dose adjustable prefilled injection pen provided by an embodiment of the present invention after being unscrewed;

[0023] Figure 6 A schematic structural diagram of a push rod nut provided in an embodiment of the present invention;

[0024] Figure 7 A schematic structural diagram of a dose limiting nut provided in an embodiment of the present invention;

[0025] Figure 8 A schematic structural diagram of a clutch hub provided in an embodiment of the present invention;

[0026] Figure 9 A schematic structural diagram of a push rod sleeve provided in an embodiment of the present invention;

[0027] Figure 10 A schematic structural diagram of an end stopper provided in an embodiment of the present invention;

[0028] Figure 11 A schematic structural diagram of a medicine bottle rack provided in an embodiment of the present invention;

[0029] Figure 12 A schematic structural diagram of a dosage hub provided in an embodiment of the present invention;

[0030] Figure 13 A schematic diagram of the internal structure of the barrel opening provided in an embodiment of the present invention;

[0031] Figure 14 A schematic diagram of the rear end structure of a multi-dose adjustable prefilled injection pen provided in an embodiment of the present invention;

[0032] Figure 15 A schematic diagram of the rear end explosion structure of a multi-dose adjustable prefilled injection pen provided by an embodiment of the present invention;

[0033] Figure 16 A schematic diagram of the rear end cross-sectional structure of a multi-dose adjustable prefilled injection pen provided in an embodiment of the present invention;

[0034] Figure 17 A schematic diagram of the installation between the clutch hub and the dosing hub provided in an embodiment of the present invention;

[0035] Figure 18A schematic diagram of the rear-end installation cross-sectional structure of a multi-dose adjustable prefilled injection pen provided by an embodiment of the present invention;

[0036] Figure 19 This is a schematic diagram of the installation structure between the dose limiting nut and the dose hub provided by an embodiment of the present invention.

[0037] The following are marked in the accompanying drawings:

[0038] Needle 1, cartridge 2, stopper 3, push rod nut 4, dose limiting nut 5, clutch hub 6, push rod sleeve 7, end stopper 8, pen cap 9, medicine bottle holder 10, push rod knob 11, medicine bottle ring 12, injection push rod 13, dose hub 14, barrel 15, injection button 16, threaded hole 41, limit ratchet 42, third groove 43, second groove 51, limit internal thread 52, first ridge 61, arc-shaped protrusion 62, transmission pawl 63, limit external thread 64, chamfered surface 71, limit pawl 72, first groove 73, hook 74 , annular outer locking protrusion 81, limiting flange 82, supporting foot 83, transmission ratchet 84, notch 101, mounting protrusion 102, limiting connection structure 103, threaded column 104, supporting ratchet 141, arc-shaped tooth groove 142, zero point mark 143, radial spline 144, adjusting external thread 145, limiting groove 146, second convex strip 147, adjusting internal thread 151, window 152, reading mark 153, third protrusion 154, limiting protrusion 155, annular mounting groove 156, force transmission cylinder 161, annular inner locking protrusion 162. DETAILED DESCRIPTION

[0039] The embodiment of the present invention discloses a multi-dose adjustable prefilled injection pen, which effectively solves the problems of inconvenient operation and poor dose adjustment effect of current injection pens.

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] See also Figures 1-19 , Figure 1 A schematic cross-sectional view of a multi-dose adjustable prefilled injection pen provided in an embodiment of the present invention; Figure 2 A schematic diagram of the explosion structure of a multi-dose adjustable prefilled injection pen provided by an embodiment of the present invention; Figure 3 A schematic diagram of the external structure of the multi-dose adjustable prefilled injection pen with the pen cap removed provided by an embodiment of the present invention; Figure 4A schematic diagram of the structure of the multi-dose adjustable prefilled injection pen provided by an embodiment of the present invention with the dose hub rotated out; Figure 5 A schematic cross-sectional view of the dosage hub of a multi-dose adjustable prefilled injection pen provided by an embodiment of the present invention after being unscrewed; Figure 6 A schematic structural diagram of a push rod nut provided in an embodiment of the present invention; Figure 7 A schematic structural diagram of a dose limiting nut provided in an embodiment of the present invention; Figure 8 A schematic structural diagram of a clutch hub provided in an embodiment of the present invention; Figure 9 A schematic structural diagram of a push rod sleeve provided in an embodiment of the present invention; Figure 10 A schematic structural diagram of a medicine bottle rack provided in an embodiment of the present invention; Figure 11 A schematic structural diagram of a medicine bottle rack provided in an embodiment of the present invention; Figure 12 A schematic structural diagram of a dosage wheel hub provided in an embodiment of the present invention; Figure 13 A schematic diagram of the internal structure of the barrel opening provided in an embodiment of the present invention; Figure 14 A schematic diagram of the rear end structure of a multi-dose adjustable prefilled injection pen provided in an embodiment of the present invention; Figure 15 A schematic diagram of the rear end explosion structure of a multi-dose adjustable prefilled injection pen provided in an embodiment of the present invention; Figure 16 A schematic diagram of the rear end cross-sectional structure of a multi-dose adjustable prefilled injection pen provided in an embodiment of the present invention; Figure 17 A schematic diagram of the installation between the clutch hub and the dosing hub provided in an embodiment of the present invention; Figure 18 A schematic diagram of the rear-end installation cross-sectional structure of a multi-dose adjustable prefilled injection pen provided by an embodiment of the present invention; Figure 19 This is a schematic diagram of the installation structure between the dose limiting nut and the dose hub provided by an embodiment of the present invention.

[0042] In a specific embodiment, the present invention provides a multi-dose adjustable prefilled injection pen, as shown in the attached Figure 1-3 As shown, the multi-dose adjustable prefilled injection pen mainly includes a pen body, an injection push rod 13, a push rod sleeve 7, a clutch hub 6, an end limiter 8 and a dose hub 14. Of course, a medicine bottle rack 10 for placing the cartridge bottle 2, a pen cap 9 mounted on the pen body, etc. can also be provided.

[0043] The injection push rod 13 is connected to the pen body via a threaded connection whose axis extends in the injection direction. This allows the injection push rod 13 to move axially relative to the pen body when it is rotated in the threading direction. Furthermore, since the cartridge 2 and the pen body are relatively fixed, typically via the vial holder 10, although other methods such as a snap-fit ​​connection or threaded connection may also be used, the injection push rod 13 can push the stopper 3 inside the cartridge 2 in the injection direction, thereby effecting injection.

[0044] The push rod sleeve 7 and the injection push rod 13 slide together in the injection direction and can transmit the torque in the injection push rod's screwing direction. Specifically, if the injection push rod 13 is provided with an external thread, one side or two opposite sides of the injection push rod 13 can be flattened. The push rod sleeve 7 is sleeved on the outside of the injection push rod 13, and the cross section is provided with a corresponding flat surface 71, such as a flat shape, to limit the rotation of the internal injection push rod 13. However, the injection push rod 13 can slide in the push rod sleeve 7 in the injection direction to achieve a sliding connection. Of course, the injection push rod 13 can also be provided with an axially extending groove, and the push rod sleeve 7 can be provided with a corresponding ridge on the inside to limit the relative rotation of the push rod sleeve 7 and the injection push rod 13 through the ridge groove.

[0045] The push rod sleeve 7 is connected to the pen body via a first set of ratchet and pawl mechanisms, preventing the push rod sleeve 7 from rotating relative to the pen body in the direction of retraction around the injection push rod 13. Furthermore, the clutch hub 6 slides with the push rod sleeve 7 in the injection direction, restricting relative rotation. Because relative rotation between the push rod sleeve 7 and the injection push rod 13 is restricted, the injection push rod 13 is prevented from rotating in the retraction direction. This allows the push rod sleeve 7, the injection push rod 13, and the clutch hub 6 to rotate only in the direction of advancement around the injection push rod 13, during which injection is performed. As the injection push rod 13 approaches, the push rod sleeve 7 rotates with it, but remains fixed relative to the pen body in the injection direction. The injection push rod 13 then slides relative to the push rod sleeve 7 in the injection direction. The clutch hub 6 and the push rod sleeve 7 are slidably matched along the injection direction and limit relative rotation. Specifically, the clutch hub 6 can be sleeved on the outside of the push rod sleeve 7, and one of the outer side surface of the push rod sleeve 7 and the inner side surface of the clutch hub 6 is provided with a convex strip extending along the injection direction, and the other is provided with a groove matching the convex strip to limit relative rotation. Specifically, first grooves 73 are respectively provided on both sides of the push rod sleeve 7, and first convex strips 61 are correspondingly provided on both opposite sides of the clutch hub 6.

[0046] The dose wheel hub 14 is rotatably connected to the pen body via a threaded connection, and axially driving the dose wheel hub 14 can propel the dose wheel hub 14 forward. Specifically, the dose wheel hub 14 and the pen body are preferably connected via a non-self-locking threaded connection. To ensure smoother rotation, sliding friction at the threaded connection between the dose wheel hub 14 and the pen body should be minimized, and lubricant can be added between the two. Of course, non-self-locking threads can be omitted, and other structures can be provided to convert a portion of the axial thrust into torque thrust to propel the dose wheel hub 14 relative to the pen body. Specifically, the dose wheel hub 14 can have an external adjustment thread 145 on the outside, while the pen body can have an internal adjustment thread 151 on the inside.

[0047] The clutch hub 6 and the dosage hub 14 are restricted from rotating in the injection direction by a snap-fit ​​structure that can be disengaged. When the snap-fit ​​structure is engaged, the dosage hub 14 can provide support to the clutch hub 6 in the opposite direction of the injection direction. This allows the clutch hub 6 to move in the injection direction, so that the snap-fit ​​structure is engaged. When the snap-fit ​​structure is engaged, relative rotation between the two is restricted. In other words, rotation of the dosage hub 14 can drive rotation of the clutch hub 6. When the snap-fit ​​structure is disengaged, the two can rotate freely relative to each other.

[0048] The end stopper 8 and the dose hub 14 are supported by a support foot 83 that can elastically deform along the injection direction, so that when the end stopper 8 is subjected to a thrust in the injection direction to elastically deform the support foot 83, the clamping structure can be prevented from being disengaged, and rotating the dose hub 14 before the support foot 83 is elastically deformed can push the clamping structure to be disengaged. Even if the clamping structure is in the engaged state at this time, simply rotating the dose hub 14 without being restricted by the end stopper 83 will force the clamping structure to be disengaged, making it impossible to transmit torque and thus unable to push the clutch hub 6 to rotate synchronously.

[0049] When using this multi-dose adjustable prefilled injection pen, the cartridge 2 is secured to the pen body, and the injection push rod 13 is brought into contact with the stopper 3 of the cartridge 2. The dose wheel 14 is now in its initial position relative to the pen body. The end stopper 8 is then pushed in the injection direction to elastically deform the support foot 83, thereby preventing the latching structure from disengaging. The end stopper 8 then transmits the injection-direction thrust to the dose wheel 14, causing it to rotate. Because the latching structure is now engaged, the dose wheel 14 drives the clutch hub 6 to rotate, which in turn drives the push rod sleeve 7 and the injection push rod 13 to initiate the injection. After the first injection is completed, the end stopper 8 is released and reset. The dose wheel 14 then needs to be returned to its initial position to facilitate metering for the next injection. The dose wheel 14 can then be rotated outward relative to the pen body. During this process, without the restraint of the end stop 8, the dose wheel 14 cannot rotate the clutch hub 6. Instead, it causes the clutch hub 6 to slide in the opposite direction of the injection direction. At this point, the injection plunger 13 and the plunger sleeve 7 remain stationary relative to the pen body until the dose wheel 14 returns to its initial position relative to the pen body, at which point injection can be resumed. However, if the dose wheel 14 is rotated excessively, the dose wheel 14 must be rotated inward. Because the end stop 8 is not subject to the injection-direction force, the clutch hub 6 will not rotate. In this multi-dose adjustable prefilled injection pen, an end stop 8 is provided. This elastic support leg 83 controls the rotational connection between the dose wheel 14 and the clutch hub 6. This allows injection to be completed by simply pressing the end stop. To adjust the dose, the dose wheel 14 only needs to be rotated. This makes operation extremely convenient and easy, and dose adjustment is simple. The overall structure is simple, with few components, easy assembly, and no metal springs or other structures are required, resulting in lower overall cost. In summary, the multi-dose adjustable prefilled injection pen can effectively solve the problems of inconvenient operation and poor dose adjustment effect of current injection pens.

[0050] Furthermore, to prevent the dose drum 14 from excessively rotating and exceeding the dose contained therein, a dose limiting nut 5 is preferably included. Specifically, the dose limiting nut 5 is threadedly connected to the clutch hub 6 and slides with the dose hub 14 along the injection direction to limit relative rotation. When the dose hub 14 rotates relative to the clutch hub 6, the dose hub 14 moves axially along the clutch hub 6, i.e., in the injection direction. When the dose hub 14 reaches a predetermined rotation angle relative to the clutch hub 6, the dose hub 14 cannot continue to rotate relative to the clutch hub 6, thereby preventing the dose hub 14 from continuing to rotate relative to the clutch hub 6. Specifically, the dose limiting nut 5 can include a limiting internal thread 52 and a second groove 51. The second groove 51 extending along the injection direction is provided on both sides of the dose limiting nut, and second ridges 147 are provided on opposite sides of the dose hub 14. The second groove 51 and the second ridge 147 are correspondingly provided on opposite sides of the dose hub 14 to limit relative rotation between the dose hub 14 and the dose limiting nut 5. Correspondingly, the outer side of the clutch hub 6 has a limiting external thread 64 to cooperate with the limiting internal thread 52. Specifically, the thread pitch between the dose limiting nut 5 and the clutch hub 6 can be smaller than the thread pitch between the dose hub 14 and the pen body, and the former can be a self-locking thread.

[0051] Furthermore, in order to prevent the end limiter 8 from rotating relative to the dose hub 14 during injection, it is preferred that the tip of the supporting foot 83 is a pawl, with the tip of the pawl facing the injection direction, and the supporting foot 83 is rod-shaped, with one end having a downwardly extending and protruding pawl as a support point, and the other end is connected to the body of the end limiter 8, so that the supporting foot 83 can be elastically bent, thereby changing the relative distance between the pawl and the body of the end limiter 8 in the injection direction.

[0052] The end of the dose wheel hub 14 has a support ratchet 141 that cooperates with the pawl on the support foot 83 to prevent relative rotation in the screwing direction of the ratchet wheel hub 14. When the ratchet wheel hub 14 is screwed in, it can drive the end stopper 8 to rotate synchronously and provide support force for the end stopper 8 in the opposite direction of the injection direction, that is, the backward direction.

[0053] Furthermore, in order to prevent the end stopper 8 from shaking randomly, especially in the injection direction, it is preferred that the end stopper 8 has a limiting flange 82, and the dose wheel hub 14 is correspondingly provided with a limiting groove 146 surrounding the limiting flange 82 to limit the range of movement of the limiting flange 82 in the injection direction, thereby limiting the range of movement of the end stopper 8 relative to the dose wheel hub 14 in the injection direction, and preferably the support foot 83 on the end stopper 8 is in a pre-tightened state.

[0054] Furthermore, in order to facilitate the setting of the snap-fit ​​structure, specifically, the clutch hub 6 can have a cam at the rear end, and a plurality of circumferentially evenly distributed arc-shaped protrusions 62 can be provided on the front side of the cam. Correspondingly, the inside of the rear end of the dose hub 14 has an annular shoulder, and the rear side of the annular shoulder has an arc-shaped tooth groove 142 that is circumferentially distributed and cooperates with the arc-shaped protrusion 62. Specifically, the arc-shaped protrusion 62 can be semi-cylindrical, and the axial direction is the radial direction of the clutch hub 6. The cross-section of the corresponding arc-shaped tooth groove 142 is semi-circular, and the tooth tip is smoothly transitioned, so that when the dose hub 14 is rotated, the clutch hub 6 jumps in the injection direction, so that the snap-fit ​​structure can easily enter and exit the snap-fit ​​state to avoid transmitting torque.

[0055] Furthermore, the rear end of the clutch hub 6 and the end stop 8 can be connected via a second set of ratchet and pawl mechanisms. Specifically, the rear end of the clutch hub 6 has drive pawls 63 disposed in opposite directions, while the end stop 8 has drive ratchets 84 within it. During injection, the dose hub 14 can transmit torque to the end stop 8, and the end stop 8 can transmit torque to the clutch hub 6. During dose adjustment, the support legs 83 disconnect the drive pawls 63 from the drive ratchets 84.

[0056] Furthermore, in order to facilitate the application of a thrust in the injection direction to the end stopper 8 during injection, an end button 16 is preferably included, wherein the end button 16 is clamped around the end stopper 8 to prevent the end torque 16 from detaching from the end stopper 8. Specifically, the end stopper 8 has an annular outer locking protrusion 81 extending in an annular manner, and the end button is correspondingly provided with an inwardly protruding annular inner locking protrusion 162, wherein the front side of the annular outer locking protrusion 81 abuts against the rear side of the annular inner locking protrusion 162. Preferably, the middle portion of the end button 16 has a force transmission cylinder 161 extending in the injection direction, wherein the front end of the force transmission cylinder 161 abuts against the end stopper 8 and is spherical to reduce rotational resistance.

[0057] Specifically, the end button 6 can be made into a cover cap shape, and the inner wall of the cap brim has the annular inner snap-in protrusion 162, the middle part of the inner side has a force transmission cylinder 161, and the end button 6 is covered on the rear end column of the end limiter 8, and the outer side of the rear end of the column has an annular outer snap-in protrusion 81, and the front end spherical part of the force transmission cylinder 161 is pressed against the middle groove of the inner bottom of the rear end column.

[0058] Furthermore, in order to facilitate the setting of the pen body, it is preferred that the pen body includes a barrel 15 and a push rod nut 4 inserted into the barrel 15. The push rod nut 4 is threadedly connected to the injection push rod 13 and is connected to the push rod sleeve 7 through the first set of ratchet and pawl mechanisms. Specifically, the barrel 15 has an opening at the front end and a limiting shoulder inside. The push rod nut 4 is inserted into the barrel 15 from the front end opening until it abuts against the limiting shoulder. The barrel 15 has a limiting protrusion 155 inside to prevent the push rod nut 4 from detaching from the barrel 15. When inserted, the push rod nut 4 is elastically deformed so that it can pass over the limiting protrusion 155. Specifically, the push rod nut 4 can have a threaded hole 41 that passes through from front to back, and a large groove body can be opened in the rear section, and the groove wall of the large groove body can be the limiting ratchet 42 of the first group of ratchet and pawl mechanism. The corresponding front end of the push rod sleeve 7 has a limiting pawl 72 of the first group of ratchet and pawl mechanism, and the outside of both sides of the large groove body has a third groove 43 extending along the injection direction, and the barrel 15 has a third protrusion 154 that cooperates with the third groove 43.

[0059] Specifically, the injection push rod 13, the push rod sleeve 7, the clutch hub 6, the dose limiting nut 5, the dose hub 14, and the barrel 15 can be sequentially arranged. In order to prevent excessive axial movement of the clutch hub 6, the rear end of the push rod sleeve 7 is preferably provided with a hook 74.

[0060] Furthermore, to facilitate dose reading, a window 152 is preferably provided on the barrel 15. The outer side of the dose wheel 14 has a spirally distributed scale so that it can sequentially pass through the window 152 during rotation. For more accurate reading, the barrel 15 preferably has a reading mark 153, preferably in the shape of an arrow. Correspondingly, the dose wheel 14 can have a zero mark 143 corresponding to the zero point of the scale, so that when the reading is zero, the zero mark 143 is aligned with the reading mark 153. To facilitate rotation, the rear end of the dose wheel 14 preferably has radial splines 144 exposed on the barrel 15 to prevent slipping.

[0061] Furthermore, to facilitate securing the cartridge, a vial holder 10 is preferably included. The vial holder is clipped onto the front end of the cartridge body. Specifically, the rear end of the vial holder 10 is inserted into the front end opening of the cartridge body 15. The rear end has a notch 101 to position the angular position of the cartridge body 15. The vial holder 10 also has an annular mounting protrusion 102 to cooperate with an annular mounting groove 156 within the opening of the cartridge body 15 to position and clamp the cartridge body in the injection direction. The rear end of the vial holder 10 has a vial ring 12. The front end of the vial ring 12 is used to abut against the vial in the vial holder 10, and the rear end abuts against the pen body. The front end of the injection plunger 13 has a plunger knob 11 that can be rotated to abut against the vial stopper. The front end of the vial holder 10 has a threaded post 104 for connecting to the needle 1. Correspondingly, a pen cover 9 is also provided, and the rear end of the pen cover 9 is snap-connected with the medicine bottle rack 10, that is, the medicine bottle rack 10 has limiting connection structures 103 on opposite sides, and the corresponding rear end of the pen body has a limiting connection structure along the inner side.

[0062] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0063] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one 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 limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-dose adjustable prefilled injection pen, characterized in that: The pen body comprises a pen body, an injection push rod, a push rod sleeve, a clutch hub, an end limiter and a dosage hub, wherein the injection push rod is connected to the pen body through a threaded connection whose axis extends in the injection direction, the push rod sleeve slides with the injection push rod along the injection direction and can transmit the torque in the direction of the injection push rod being screwed in, the push rod sleeve and the pen body are connected through a first set of ratchet and pawl mechanisms to prevent the push rod sleeve from rotating relative to the pen body in the direction of the injection push rod being screwed back, the clutch hub slides with the push rod sleeve in the injection direction and limits relative rotation, the dosage hub is rotationally connected to the pen body through a thread and can push the dosage hub to be screwed in when the dosage hub is axially driven, and the clutch hub and the dosage hub are connected by a clamping structure that can be disengaged along the injection direction. To limit rotation, the end limit piece and the dose wheel hub are supported by a supporting foot that can elastically deform along the injection direction. When the end limit piece is subjected to the thrust in the injection direction to elastically deform the supporting foot, it can prevent the clamping structure from disengaging, and rotating the dose wheel hub before the supporting foot is elastically deformed can push the clamping structure to disengage; the tip of the supporting foot is a pawl, and the tip of the pawl faces the injection direction, and the end of the dose wheel hub has a ratchet that cooperates with the pawl on the supporting foot to prevent relative rotation in the screw-in direction; the end limit piece has a limiting flange, and the dose wheel hub is correspondingly provided with a limiting groove surrounding the limiting flange to limit the range of movement of the limiting flange in the injection direction and put the supporting foot in a pre-tightened state.

2. The multi-dose adjustable prefilled injection pen according to claim 1, characterized in that: It also includes a dose limiting nut, which is threadedly connected to the clutch hub and slides with the dose hub along the injection direction and limits relative rotation, so that when the dose hub rotates relative to the clutch hub, the dose limiting nut moves along the axial direction of the clutch hub.

3. The multi-dose adjustable prefilled injection pen according to claim 1, characterized in that: The supporting foot is in the shape of a rod, and one end of the rod has a downwardly extending and protruding pawl as a supporting point, so that the supporting foot can be elastically bent.

4. The multi-dose adjustable prefilled injection pen according to claim 1, characterized in that: The clutch hub has a convex disc at the rear end, and a plurality of circumferentially evenly distributed arcuate protrusions at the front side. The dosage hub has an annular shoulder inside the rear end, and the annular shoulder has circumferentially distributed arcuate tooth grooves on the rear side that match the arcuate protrusions.

5. The multi-dose adjustable prefilled injection pen according to claim 1, characterized in that: It also includes an end button, which is clamped on the end limit piece around the end button and has a force transmission cylinder extending along the injection direction in the middle. The front end of the force transmission cylinder is against the end limit piece and is spherical.

6. The multi-dose adjustable prefilled injection pen according to claim 2, characterized in that: The pen body includes a barrel and a push rod nut clamped into the barrel. The push rod nut is threadedly connected to the injection push rod and is connected to the push rod sleeve through the first set of ratchet and pawl mechanisms.

7. The multi-dose adjustable prefilled injection pen according to claim 6, characterized in that: The injection push rod, the push rod sleeve, the clutch hub, the dose limiting nut, the dose hub and the body are sequentially sleeved.

8. The multi-dose adjustable prefilled injection pen according to claim 1, characterized in that: A window is provided on the pen body, and a spirally distributed scale is provided on the outer side of the dosage wheel hub so that the scales can pass through the window in sequence when the dosage wheel hub is screwed in.

9. The multi-dose adjustable prefilled injection pen according to claim 6, characterized in that: It also includes a medicine bottle rack clamped to the front end of the barrel, the rear end of the medicine bottle rack has a medicine bottle ring, the front end of the medicine bottle ring is used to abut against the medicine bottle in the medicine bottle rack, and the rear end is used to abut against the push rod nut, the front end of the injection push rod has a push rod knob that can be rotated to abut against the medicine bottle stopper, and the front end of the medicine bottle rack has a threaded column for connecting a needle.

10. The multi-dose adjustable prefilled injection pen according to claim 9, characterized in that: It also includes a pen cover, the rear end of which is clamped with the medicine bottle rack.

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