CN215690639U - Injection pen driving mechanism - Google Patents

Abstract

The application relates to an injection pen driving mechanism, which comprises a shell, a mounting bracket, a plunger rod, a driving spring and a locking sleeve; the plunger rod is provided with a plunger convex part; the mounting bracket is provided with a driving pipe part which is provided with a plunger sliding groove for the plunger convex part to extend out and for the plunger convex part to axially slide; the locking sleeve is circumferentially and rotatably arranged on the outer side of the driving tube part and is provided with a locking stepped structure for the plunger convex part to abut to restrain the plunger rod from moving towards the injection direction; defining a circumferential direction of an inclination direction of the locking stepped structure in a direction from the front end to the rear end as an unlocking direction; the injection pen driving mechanism is further provided with a tail cap assembly which drives the locking sleeve to rotate towards the unlocking direction so that the plunger convex part moves axially step by step along the locking stepped structure. The present application has the effect of less pressure fluctuations being exerted on the piston of the cartridge bottle during injection.

Description

Injection pen driving mechanism

Technical Field

The application relates to the field of injectors, in particular to an injection pen driving mechanism.

Background

The injection pen for multiple injections is an injection pen capable of injecting a liquid medicine in a medicine tube into a patient in several divided injections. The injection pen for multiple injection can be used for multiple times, so that the requirements of patients are met. The existing injection pen for multiple injections is internally provided with a driving mechanism, and during injection, the driving mechanism transmits the pushing force applied to a tail cover by a user to a piston of a cassette bottle, so that the liquid medicine in the cassette bottle is extruded out.

With respect to the related art in the above, the inventors consider that the pressure applied to the cartridge piston by the above-described injection pen driving mechanism at the time of injection is unstable.

SUMMERY OF THE UTILITY MODEL

In order to minimize pressure fluctuations on the cartridge piston during injection, an injection pen drive mechanism is provided.

The application provides an injection pen actuating mechanism adopts following technical scheme:

an injection pen driving mechanism comprises a shell, a mounting bracket, a plunger rod, a driving spring and a locking sleeve, wherein the mounting bracket is mounted on the shell and is circumferentially locked with the shell; the side wall of the rear end of the plunger rod is provided with a plunger convex part; the mounting bracket is provided with a driving tube part for the axial sliding mounting of the plunger rod, and the driving tube part is provided with a plunger sliding groove for the axial sliding of the plunger convex part and extending out of the plunger convex part; the locking sleeve is circumferentially and rotatably arranged on the outer side of the driving tube part and is provided with a locking stepped structure for the plunger convex part to abut to restrain the plunger rod from moving towards the injection direction; defining a circumferential direction of an inclination direction of the locking stepped structure in a direction from the front end to the rear end as an unlocking direction; the injection pen driving mechanism is further provided with a tail cap assembly which drives the locking sleeve to rotate towards the unlocking direction so that the plunger convex part moves axially step by step along the locking stepped structure.

Through adopting above-mentioned technical scheme, above-mentioned injection pen actuating mechanism drives the locking sleeve rotation through the tail-hood subassembly when using, can make the restraint of locking stair structure to the plunger convex part disappear in the locking sleeve to make the plunger rod move one section distance to the injection direction, this section distance can be controlled through the interval between two adjacent ladder surfaces in the locking stair structure. The injection pen driving mechanism does not transmit the force of a user to the piston of the cassette bottle through the built-in transmission mechanism, but presses the plunger rod through the driving spring, so that the driving force of the plunger rod moving towards the injection direction is kept constant, the speed of the injection pen with the injection pen driving mechanism is kept constant when liquid medicine is input into a patient, the liquid medicine amount input into the patient in unit time is stable, and the experience feeling of the patient when the liquid medicine is injected is improved.

Optionally, the tail cap assembly is rotatably mounted on the housing, the formations in the tail cap assembly being configured to lock circumferentially; the tail cover assembly comprises a key and a tail end spring, the key is mounted on the shell and is provided with a first station and a second station in the axial direction, and the second station is positioned behind the first station; the key is circumferentially limited when moving from the second station to the first station; the locking sleeve is provided with a guide surface arranged towards the tail end direction; the key is provided with a driving surface which is used for being abutted with the guide surface to drive the locking sleeve to rotate towards the unlocking direction.

Through adopting above-mentioned technical scheme, when using above-mentioned injection pen actuating mechanism to inject, through the button in the tail-hood subassembly of pushing down, press the button to first station from the second station for locking the sleeve and rotating the appointed angle to the unblock direction under the cooperation of spigot surface and drive face, thereby make the plunger convex part remove to next step face from the one step face that locks the stair structure, realize the purpose of injection, this kind of injection operation is comparatively convenient.

Optionally, the locking sleeve is further provided with a locking hook portion, and the key is provided with a hook groove; the hook groove is configured to be inserted by the locking hook when the key is in the first station, restricting movement of the key in the axial direction.

Through adopting above-mentioned technical scheme, when the button is pressed and is removed to the in-process of first station from the second station, the locking sleeve can rotate appointed angle towards the unblock direction to make locking hook portion insert the hook inslot of button, thereby realize locking the axial of button, make the button can not resume to second station department under the effect of tail end spring. When the patient needs to use the injection pen of many times injection next time to inject, need rotate tail-hood subassembly to make locking hook portion deviate from in the hook groove of button, the button is replied to the second station from first station, makes to press the button once more and orders about locking sleeve circumferential direction. The setting reduces the probability of the waste of the liquid medicine caused by the fact that the patient mistakenly presses the key after one injection is finished.

Optionally, the key has a driving lug plate extending towards the locking sleeve, and the driving surface and the hook groove are both disposed on the driving lug plate.

Through adopting above-mentioned technical scheme, all set up drive face and hook groove on the drive flange for the compact structure of button.

Optionally, the tail cover assembly comprises a limiting pipe sleeve sleeved outside the plunger rod, and the limiting pipe sleeve is provided with a limiting stepped structure for abutting the convex part of the plunger; the limiting stepped structure is positioned on one side of the plunger convex part, which is back to the locking stepped convex part; the limit step structure is configured such that the drive surface is directly opposite the guide surface when the plunger boss abuts on the limit step structure.

By adopting the technical scheme, after one-time injection is completed, the key is positioned at the first station and is locked by the locking hook part of the locking sleeve, so that the tail cover assembly needs to be rotated, and the key in the tail cover assembly is separated from the locking hook part and returns to the second station. In the process, the limiting step structure of the limiting pipe sleeve is matched with the plunger convex part, so that the rotation angle of the tail cover assembly towards the unlocking direction is limited, the angle can be kept consistent with the specified angle of the locking sleeve, the driving surface in the key can be opposite to the guide surface on the locking sleeve, and the stability of the injection pen for multiple injections in the using process is improved.

The structure limitation also enables the key to abut against the limiting step structure in the process of moving from the second station to the first station, so that the key is limited from deflecting towards the unlocking direction in the injection process.

Optionally, the tail cap assembly further comprises a fixed ratchet wheel circumferentially limited and mounted on the housing, and the tail cap assembly comprises a tail end ratchet wheel, and the tail end ratchet wheel and the fixed ratchet wheel are connected through a ratchet structure, so that the fixed ratchet wheel can rotate in an unlocking direction relative to the tail end ratchet wheel, and the fixed ratchet wheel is limited from rotating in a back-to-unlocking direction relative to the tail end ratchet wheel; the tail end spring drives the tail end ratchet wheel to have a tendency of always abutting against the end part of the fixed ratchet wheel section.

By adopting the technical scheme, the tail end ratchet wheel is circumferentially and relatively locked with other components in the tail cover assembly, and the tail end ratchet wheel is matched with the fixed ratchet wheel, so that the tail cover assembly and the keys in the tail cover assembly can only rotate in the unlocking direction in the circumferential direction, the tail cover assembly cannot rotate in the direction opposite to the unlocking direction, the stability of the injection pen for multiple injections is improved, and the probability of misoperation of the injection pen for multiple injections in the use process is reduced.

Optionally, the fixed ratchet is axially slidably mounted on the housing; the locking sleeve and the fixed ratchet are also connected by a ratchet structure such that the locking sleeve is rotatable relative to the fixed ratchet in an unlocking direction and restricts rotation of the locking sleeve relative to the fixed ratchet in a back-to-unlocking direction; the tail end spring drives the fixed ratchet wheel to have a tendency of always abutting against the end of the locking sleeve.

Through adopting above-mentioned technical scheme, the cooperation of locking sleeve and fixed ratchet for the locking sleeve only can rotate towards the unblock direction in circumference, has restricted locking sleeve to rotate towards the unblock direction of keeping away from, thereby has improved the injection pen's of many times injection stability and has reduced the injection pen of many times injection and has taken place the probability of maloperation in the use.

Optionally, the tail cap assembly further comprises a screw cap which is circumferentially and rotatably mounted at the tail end of the housing.

Through adopting above-mentioned technical scheme, spiral cover circumference rotation installs the tail end at the casing for thereby the user can drive the tail-hood subassembly through rotating the spiral cover and rotate, has made things convenient for the user to rotate whole tail-hood subassembly.

Optionally, the number of the plunger protrusions on the plunger rod is two, and the two plunger protrusions are symmetrically arranged about the axis of the plunger rod.

Through adopting above-mentioned technical scheme, the setting of two plunger convex parts for the axial of plunger rod on the installing support slides more stably.

In summary, the present application includes at least one of the following beneficial technical effects:

1. the pressure applied to the cartridge bottle piston by the injection pen driving mechanism in the injection process is from the driving spring, so that the speed of the injection pen for multiple injections is kept constant when liquid medicine is input into a patient, the liquid medicine amount input into the patient in unit time is stable, and the experience of the patient when the liquid medicine is injected is improved;

2. the locking sleeve is driven to rotate towards the unlocking direction by pressing the key, so that the injection operation of the injection pen driving mechanism is convenient;

3. the cooperation of the fixed ratchet wheel and the tail end ratchet wheel, the cooperation of the fixed ratchet wheel and the locking sleeve, and the cooperation of the limiting stepped structure and the plunger convex part in the limiting pipe sleeve enable the use of the injection pen for multiple injections to have the limitation of operation steps, enable the next operation to be impossible under the condition that the previous operation is not completed, improve the stability of the injection pen for multiple injections and reduce the probability of misoperation of the injection pen for multiple injections in the use process.

Drawings

Fig. 1 is an exploded view of the driving mechanism of the injection pen in this embodiment.

Fig. 2 is a sectional view of the housing mounting bracket of the present embodiment in cooperation.

Fig. 3 is an enlarged schematic view at a in fig. 2.

Fig. 4 is a schematic view of the engagement of the mounting bracket and plunger rod in this embodiment.

Fig. 5 is a schematic view of the mounting bracket, plunger rod and drive spring engagement in this embodiment.

Fig. 6 is a schematic structural view of the locking sleeve in the present embodiment.

Fig. 7 is a schematic view of the internal structure of the locking sleeve in the present embodiment.

Fig. 8 is a schematic sectional view showing the engagement of the rear housing, the connecting base, the plunger rod, the driving spring, the locking sleeve, the tail end assembly and the fixed ratchet in this embodiment.

Fig. 9 is an enlarged schematic view at B in fig. 8.

FIG. 10 is a schematic view of the housing, fixed ratchet and locking sleeve in cooperation.

Fig. 11 is a schematic view of the cooperation of the screw cap, the housing and the key.

Fig. 12 is a schematic view of the front end structure of the screw cap.

Fig. 13 is a schematic diagram of the front end structure of the key.

FIG. 14 is a schematic view of the key engaging the locking sleeve in the first position.

FIG. 15 is a schematic view of the key engaging the locking sleeve in the second position.

FIG. 16 is a schematic view of the engagement of the button, the tail spring, the tail ratchet and the fixed ratchet.

FIG. 17 is a schematic view of the engagement of the aft ratchet, the stop collar and the mounting bracket.

Fig. 18 is a schematic view of the engagement of the retaining sleeve, mounting bracket and plunger rod.

FIG. 19 is a schematic view of the engagement of the stop collar and the trailing ratchet.

Description of reference numerals: 1. a housing; 11. installing a tube cavity; 12. a containing groove; 13. accommodating the step surface; 14. a first bayonet; 15. a color development window; 16. installing a chute; 17. a tail end portion; 171. a tail cover ring groove; 172. a support ring; 18. a restraining collar; 2. mounting a bracket; 21. a plug-in part; 211. a first elastic buckle; 212. inserting grooves; 22. a positioning ring groove; 23. a butt joint plate; 24. a drive tube portion; 241. a drive lumen; 242. inserting a spring into the column; 243. a plunger slide groove; 244. a front drive tube; 245. a rear drive tube; 3. a plunger rod; 31. a plunger head; 32. a spring slot; 33. a plunger boss; 4. a locking sleeve; 41. a front body portion; 411. positioning the ring edge; 42. a rear body portion; 431. a first step surface; 432. a second step surface; 433. a third step surface; 434. a fourth step surface; 435. a fifth step surface; 44. a color development convex ring; 441. a color development ring groove; 442. a first color-displaying block; 443. a second color development block; 444. a third color development block; 445. a fourth color development block; 446. a fifth color development block; 447. a sixth color development block; 45. a second ratchet; 46. a guide projection; 461. a guide surface; 47. a locking hook portion; 5. a drive spring; 6. fixing the ratchet wheel; 61. a fixed protrusion; 62. a first ratchet; 63. a fourth ratchet; 71. screwing a cover; 711. a limiting bump; 712. limiting and flanging; 713. a flanging ring groove; 714. a first locking bar; 72. pressing a key; 721. an accommodating cavity; 722. a front key body; 723. a rear key body; 7231. a first locking groove; 724. driving the convex plate; 7241. a drive face; 7242. a hook groove; 725. a second locking groove; 726. locking the insert column; 7261. a fourth locking groove; 73. a tail end spring; 74. a tail end ratchet wheel; 741. a lower ratchet wheel part; 7411. a second locking bar; 7412. a tail end spring slot; 742. an upper ratchet portion; 743. a third ratchet; 744. a ratchet wheel through hole; 7441. a ratchet wheel front hole; 7442. a ratchet wheel rear hole; 745. a third locking groove; 746. a third elastic buckle; 75. a limiting pipe sleeve; 751. a limiting pipe part; 7511. limiting the tube cavity; 752. a transition duct section; 7521. a transition lumen; 753. a locking tube portion; 7531. locking the lumen; 7532. a third locking bar; 7533. a fourth locking bar; 7534. a third bayonet; 754. limiting stepped holes; 7541. a first step side; 7542. a second step side; 7543. a third step side; 7544. a fourth step side; 7545. a fifth step side; 755. a structural convex ring; 7551. and (5) structural gaps.

Detailed Description

The present application is described in further detail below with reference to figures 1-19.

In the present application, when the term "front end portion/end" is used, this refers to the portion/end of the injection pen drive mechanism or components thereof that is close to the injection area of the human body during injection; accordingly, when the term "rear end portion/end" is used, this refers to the portion/end of the injection pen drive mechanism or components thereof that is remote from the injection area of the body during injection. A direction from the rear end portion to the front end portion of the injection pen driving mechanism is defined as an injection direction, and a state of the injection pen driving mechanism when not in use is defined as an initial state of the injection pen driving mechanism.

The embodiment of the application discloses an injection pen driving mechanism. Referring to fig. 1, the injection pen driving mechanism includes a housing 1, a mounting bracket 2 mounted on the housing 1, a plunger rod 3 axially slidably mounted in the housing 1, a locking sleeve 4 circumferentially rotatably mounted in the housing 1 and sleeved outside the plunger rod 3, a driving spring 5 mounted in the mounting bracket 2 and driving the plunger rod 3 to have a tendency of axially moving towards the injection direction all the time, a fixed ratchet 6 mounted in the housing 1, and a tail cap assembly circumferentially rotatably mounted on the housing 1.

Referring to fig. 1, the tail cap assembly includes a screw cap 71, a button 72, a tail spring 73, a tail ratchet 74 and a limit socket 75. Wherein the screw cap 71, the key 72, the tail end spring 73, the tail end ratchet 74 and the limit socket 75 are configured to be circumferentially locked with each other.

Referring to fig. 2 and 3, the housing 1 is constructed in a hollow tubular structure, and the housing 1 has a mounting lumen 11 having a circular cross-section. The housing 1 is provided with a receiving groove 12 at the front end portion of the mounting cavity 11 in the circumferential direction, and a receiving stepped surface 13 is formed on the bottom surface of the receiving groove 12. The housing 1 is provided with two first bayonets 14 penetrating through the inner and outer surfaces on the side wall of the accommodating groove 12.

Referring to fig. 2 and 3, the mounting bracket 2 has an insertion part 21 inserted into the inner cavity of the housing 1 from the front end direction at the rear end part. The rear insertion part 21 has a hollow cylindrical structure. The insertion portion 21 is provided with two first elastic buckles 211 which are in one-to-one correspondence with the two first bayonets 14 and can be inserted into the first bayonets 14 on the outer wall, so that the mounting bracket 2 can be in a locking state relative to the housing 1 in the axial direction and the circumferential direction. And a positioning ring groove 22 is formed between the rear end of the insertion part 21 and the receiving stepped surface 13 when the insertion part 21 is inserted into the housing 1.

Referring to fig. 2 and 3, the mounting bracket 2 is further provided with an abutment plate 23 at the outer wall. When the insertion part 21 of the mounting bracket 2 is inserted into the housing 1, the front end of the housing 1 abuts on the rear end surface of the abutting plate 23.

Referring to fig. 4 and 5, the mounting bracket 2 is provided with a drive tube portion 24 arranged coaxially with the socket portion 21 and sealed at the rear end thereof at the rear end face of the socket portion 21. The drive tube portion 24 has an outer diameter smaller than that of the socket portion 21 so that a stepped surface is formed at the rear end of the socket portion 21.

Referring to fig. 4 and 5, the mounting bracket 2 has an insertion groove 212 opened at the distal end thereof in the insertion portion 21, and a driving tube cavity 241 communicating with the insertion groove 212 in the driving tube portion 24. Wherein the drive lumen 241 and the drive tube portion 24 are coaxially arranged. The drive tube 24 is provided coaxially with a spring insertion post 242 for receiving the drive spring 5 at the rear end of the drive tube cavity 241.

Referring to fig. 4 and 5, the plunger rod 3 is coaxially mounted within the drive lumen 241, and the forward end of the plunger rod 3 is provided with a plunger head 31 for pressing against the cartridge piston. The plunger rod 3 is coaxially provided with a spring groove 32 at the rear end surface for accommodating the driving spring 5. When the plunger rod 3 is arranged in the drive lumen 241, the front end of the drive spring 5 abuts on the front end surface of the spring groove 32 and the rear end of the drive spring 5 abuts on the rear end surface of the drive lumen 241, so that the plunger rod 3 has a tendency to move axially always in the injection direction.

Referring to fig. 4 and 5, the plunger rod 3 is circumferentially provided with two plunger protrusions 33 at the rear end portion of the outer side wall. The driving lumen 241 is provided with plunger slide grooves 243 which correspond to the two plunger protrusions 33 one by one and are used for allowing the plunger protrusions 33 to slide axially. The mounting bracket 2 has a notch formed in the rear end surface of the insertion part 21, the notch communicating with the plunger slide groove 243 and allowing the plunger protrusion 33 to pass therethrough, so that the plunger rod 3 can be mounted to the driving lumen 241 from the notch of the insertion groove 212.

Referring to fig. 6 and 7, the locking sleeve 4 is a hollow tubular structure. The lock sleeve 4 includes a front body portion 41 and a rear body portion 42 in this order in the front-end to rear-end direction. The front body portion 41 has an outer diameter larger than the rear body portion 42, and the front body portion 41 also has an inner diameter larger than the rear body portion 42.

Referring to fig. 3 and 6, the front end of the front body portion 41 is provided with a positioning ring rim 411 inserted into the positioning ring groove 22, and when the locking sleeve 4 is mounted in the housing 1, the positioning ring rim 411 is positioned in the positioning ring groove 22 so that the locking sleeve 4 is restricted from moving axially in the housing 1.

Referring to fig. 5 and 7, the locking sleeve 4 is provided at its inner surface with two locking step structures corresponding one-to-one to the two plunger protrusions 33. The locking step structure is constituted by a convex portion on the inner wall of the locking sleeve 4, and includes a plurality of locking step surfaces against which the plunger convex portion 33 abuts to restrict the axial movement of the plunger rod 3. Wherein, five locking step surfaces are arranged in the locking step structure. The five locking step surfaces are a first step surface 431, a second step surface 432, a third step surface 433, a fourth step surface 434 and a fifth step surface 435 in sequence along the direction from the rear end to the front end. A circumferential direction of an inclination direction of the locking stepped structure in a direction from the front end to the rear end is defined as an unlocking direction.

Referring to fig. 5 and 7, in an initial state, that is, when the injection pen for multiple injections is not used, the plunger protrusion 33 of the plunger rod 3 abuts against the first step surface 431, and after the locking sleeve 4 is rotated by a predetermined angle in the unlocking direction, the plunger protrusion 33 and the first step surface 431 are disengaged, and an injection stroke is formed between the plunger protrusion 33 and the second step surface 432, and the plunger rod 3 is moved in the injection direction until the plunger protrusion 33 and the second step surface 432 abut against each other by the drive spring 5. When the second injection is performed, the locking sleeve 4 needs to be rotated again by a specified angle in the unlocking direction. The widths of the locking stepped surfaces in the locking stepped structure are consistent, namely the specified angle of each rotation is also consistent. In the present embodiment, the specified angle is 25 °.

The first injection stroke between the first step surface 431 and the second step surface 432 is an exhaust injection stroke, and the height of the exhaust injection stroke is 3 mm. The rest two adjacent locking step faces are 10mm in thickness. When plunger boss 33 slides down fifth step 435, plunger rod 3 drives the cartridge piston forward until the injection of the medicinal solution in the cartridge is completed, because the restraint of the locking step structure in locking sleeve 4 is lost.

Referring to fig. 6, the outer side wall of the locking sleeve 4 is provided with a color developing convex ring 44 in the circumferential direction. The color developing convex ring 44 has a color developing ring groove 441 circumferentially formed on an outer wall thereof, and color developing blocks are provided at intervals in the color developing ring groove 441. The number of the color development blocks is six, and the color development blocks sequentially include a first color development block 442, a second color development block 443, a third color development block 444, a fourth color development block 445, a fifth color development block 446, and a sixth color development block 447 in the unlocking direction. And the circumferential included angle between the adjacent color development blocks is 25 deg. The color development blocks are coated with different colors on the outer side surface and used for distinguishing the colors of different color development blocks.

Referring to fig. 8 and 9, the casing 1 is provided with a color development window 15 penetrating the inner and outer surfaces on the outer side wall for observing the opposing color development blocks.

With reference to fig. 5, 7, 8, and 9, when the plunger boss 33 abuts on the first step face 431, the first color development block 442 is opposed to the color development window 15; when the plunger convex portion 33 abuts on the second step surface 432, the second color development block 443 faces the color development window 15; when the plunger convex portion 33 abuts on the third step surface 433, the third color development block 444 faces the color development window 15; when the plunger convex portion 33 abuts on the fourth step surface 434, the fourth color development block 445 faces the color development window 15; when the plunger convex part 33 abuts on the fifth stepped surface 435, the fifth color development block 446 faces the color development window 15; when the plunger convex portion 33 slides down from the fifth stepped surface 435, the sixth color development block 447 is opposed to the color development window 15.

Referring to fig. 10, the fixed ratchet 6 is mounted within the housing 1. The fixed ratchet 6 is evenly arranged with two fixing protrusions 61 in the outer side wall circumferential direction. The casing 1 is provided with two mounting sliding grooves 16 which correspond to the two fixing protrusions 61 one to one and are used for the sliding of the fixing protrusions 61 in the circumferential direction of the inner wall. The two mounting runners 16 are arranged axially and extend through both ends of the housing 1, so that the fixing ratchet 6 can be loaded into the housing 1 from the front end or the rear end of the housing 1, and the fixing ratchet 6 can move axially within the housing 1.

Referring to fig. 10, the fixed ratchet 6 is located on the rear end side of the locking sleeve 4. The fixed ratchet 6 is provided with a ring of first ratchet teeth 62 at a proximal end, the locking sleeve 4 is provided with a ring of second ratchet teeth 45 at a rear end which are engaged with the first ratchet teeth 62, and the engagement of the first ratchet teeth 62 and the second ratchet teeth 45 forms a ratchet structure between the fixed ratchet 6 and the locking sleeve 4, so that the locking sleeve 4 can rotate relative to the fixed ratchet 6 in an unlocking direction and the locking sleeve 4 is restricted from rotating relative to the fixed ratchet 6 in a reverse unlocking direction. Wherein, the tail cap component is abutted against the far end of the fixed ratchet 6, and drives the fixed ratchet 6 to have the tendency of always abutting against the rear end of the locking sleeve 4.

Referring to fig. 11 and 12, the housing 1 is provided at a rear end portion with a tail end portion 17 for mounting the screw cap 71. The tail end 17 is of tubular construction arranged coaxially with the housing 1. The rear end portion 17 is provided with a tail cover ring groove 171 in the circumferential direction of the front end portion. The forward end of the aft end 17 is also provided with a ring of support rings 172. The screw cap 71 is provided with four stopper protrusions 711 which are capable of being engaged into the tail cap ring groove 171 and move in the circumferential direction of the tail cap ring groove 171, at regular intervals in the circumferential direction at the front end portion of the inner wall. The rotary cover 71 is further provided with a limit flange 712 folded inwards at the rear end, and a flange ring groove 713 for inserting the rear end edge of the tail end 17 is formed between the limit flange 712 and the inner wall of the rotary cover 71.

Referring to fig. 11 and 12, the screw cap 71 is made of plastic and has a small thickness so that the screw cap 71 can be mounted on the rear end 17 of the housing 1 by slight deformation. When the screw cap 71 is mounted on the tail end portion 17, the four limit protrusions 711 of the screw cap 71 are inserted into the tail end annular groove, and the rear end edge of the tail end portion 17 is inserted into the burring annular groove 713 of the screw cap 71, so that the screw cap 71 is rotatably mounted on the tail end portion 17 and the axial displacement relative to the tail end portion 17 is limited.

Referring to fig. 11, the housing 1 is provided with a ring of restricting collars 18 at circumferentially spaced intervals at the rear end portion of the inner wall. Wherein, the limit convex ring is provided with a fracture at the mounting chute 16, so that the mounting chute 16 is not separated.

Referring to fig. 11 and 13, the key 72 is a hollow cylindrical key 72 structure and has a receiving cavity 721 with an open front end. The key 72 includes a front key body 722 and a rear key body 723 in order in a front-to-rear direction. The outer diameter of the rear key 723 is smaller than the outer diameter of the front key 722, and the outer diameter of the front key 722 is larger than the inner diameter of the limiting convex ring 18, so that the key 72 is installed into the housing 1 from the front end of the housing 1, and the key 72 cannot be disengaged from the rear end opening of the housing 1 due to the arrangement of the limiting convex ring.

Referring to fig. 11, the rear key body 723 is uniformly provided with two axially arranged first lock grooves 7231 in the outer side wall circumferential direction. The first lock groove 7231 forms an opening at the rear end of the rear key body 723. The rotary cover 71 is uniformly provided with two first locking strips 714 which are in one-to-one correspondence with the first locking grooves 7231 and can be inserted into the first locking grooves 7231 on the circumferential direction of the inner ring side surface of the limiting flange 712, so that the rotary cover 71 and the key 72 can be locked relatively in the circumferential direction.

Referring to fig. 14 and 15, the push button 72 is provided with two driving protruding plates 724 extending toward the locking sleeve 4 at the front end of the front button body 722. A driving surface 7241 is formed between the front edge of the driving protrusion 724 and the sidewall facing the unlocking direction, and a hook groove 7242 is formed on the sidewall of the driving protrusion 724 facing away from the unlocking direction.

Referring to fig. 14 and 15, the lock sleeve 4 is provided with a guide projection 46 for abutting against the driving projection plate 724 at a rear end portion of the color development projection ring 44. The guide projection 46 has a guide surface 461 formed between a rear edge thereof and a side wall on a side facing away from the unlocking direction, against which the drive surface 7241 abuts. The locking sleeve 4 is further provided at a rear end portion of the outer wall with a locking hook 47 for insertion into the hook groove 7242 of the driving lug 724. When the lock hook 47 is inserted into the hook groove 7242 of the drive protrusion, the lock hook 47 can be disengaged from the hook groove 7242 by rotating the key 72 relative to the lock sleeve 4 in the unlocking direction.

Referring to fig. 14 and 15, the key 72 is axially slidably mounted on the housing 1 and has a first position and a second position in the axial direction, and the first position is located at the front end of the second position.

Referring to fig. 14, when the key 72 is at the first station, the lock hook 47 of the lock sleeve 4 can be inserted into the hook groove 7242 of the key 72 so that the key 72 can be held at the first station.

Referring to fig. 11 and 15, when the push button 72 is in the second position, the stepped surface of the push button 72 where the front key body 722 and the rear key body 723 are connected abuts on the front end surface of the restriction collar 18.

Referring to fig. 14 and 15, when the multi-shot medicine injection driving apparatus is in the initial position, the lock sleeve 4 is in the first position, the lock hook 47 of the lock sleeve 4 is inserted into the hook groove 7242, the tail spring 73 is in a compressed state, and the push button 72 can be rotated 25 ° in the unlocking direction, so that the lock hook 47 of the lock sleeve 4 is disengaged from the hook groove 7242, the push button 72 moves from the first position to the second position, and the driving surface 7241 of the driving protrusion 724 is aligned with the guide surface 461 of the lock sleeve 4.

Referring to fig. 13 and 16, the tail ratchet 74 is disposed within the receiving cavity 721 of the key 72. The trailing ratchet 74 includes a lower ratchet portion 741 and an upper ratchet portion 742 in this order in a front-to-rear direction. The cross sections of the lower ratchet part 741 and the upper ratchet part 742 are circular, and the outer diameter of the lower ratchet part 741 is larger than that of the upper ratchet part 742.

Referring to fig. 13 and 16, the outer side wall of the lower ratchet part 741 is uniformly provided with two axially arranged second locking strips 7411 in the circumferential direction. The inner wall of the key 72 is provided with second locking grooves 725 corresponding to the two second locking strips 7411 one by one and allowing the second locking strips 7411 to be slidably installed in the axial direction, so as to realize the relative locking of the tail ratchet 74 and the key 72 in the circumferential direction.

Referring to fig. 16, the lower ratchet part 741 has a rear end spring slot 7412 along the edge of the upper ratchet part 742 at the rear end surface. The front end of the tail spring 73 is inserted into the tail spring groove 7412, and the rear end of the tail spring 73 abuts against the top surface of the accommodation cavity 721 of the key 72.

Referring to fig. 16, the tail ratchet 74 is circumferentially arranged with one turn of the third ratchet 743 at the bottom. The top surface of the fixed ratchet 6 is provided with a ring of fourth ratchet teeth 63 which mesh with the third ratchet teeth 743. The cooperation of the third ratchet 743 and the fourth ratchet 63 forms a ratchet structure between the tail ratchet 74 and the fixed ratchet 6, which allows the tail ratchet 74 to rotate in the unlocking direction relative to the fixed ratchet 6 and restricts the rotation of the tail ratchet 74 in the back-to-back unlocking direction relative to the fixed ratchet 6. Wherein, the tail end spring 73 drives the tail end ratchet 74 to have the tendency of always abutting against the rear end of the fixed ratchet 6.

Referring to fig. 17, the limit pipe housing 75 includes a limit pipe portion 751, a transition pipe portion 752 connected to a rear end of the limit pipe portion 751, and a lock pipe portion 753 connected to a rear end of the transition pipe portion 752 in this order from a front end to a rear end. The lumen of the limiting tube 75 comprises, in order in the direction from the front end to the rear end, a limiting lumen 7511 corresponding to the limiting tube portion 751, a transition lumen 7521 corresponding to the transition tube portion 752, and a locking lumen 7531 corresponding to the locking tube portion 753. Wherein, the cross sections of the limiting tube cavity 7511, the transition tube cavity 7521 and the locking tube cavity 7531 are all circular, and the outer diameter is gradually reduced.

Referring to fig. 17, the drive tube portion 24 includes a front drive tube 244 and a rear drive tube 245 in this order in the front-to-rear direction. The outer diameter of the front drive tube 244 is larger than the outer diameter of the rear drive tube 245. Wherein the plunger chute 243 is arranged on the front drive tube 244. When the limit tube nest 75 is mounted outside the drive tube part 24, the limit tube part 751 is arranged outside the front drive tube 244, and the rear end of the front drive part abuts on the stepped surface where the limit tube cavity 7511 and the transition tube cavity 7521 communicate; the transition tube portion 752 is disposed outside the rear drive tube 245, and the rear end of the rear drive tube 245 abuts on a stepped surface where the transition lumen 7521 and the locking lumen 7531 communicate.

Referring to fig. 18, the stopper tube portion 751 is formed with a stopper stepped hole 754 through which the plunger convex portion 33 passes. The stopper stepped hole 754 is provided with a stopper stepped structure for abutting against the plunger convex portion 33 on a side of the plunger convex portion 33 facing away from the unlocking direction. The limiting step structure is a limiting step cross section, and sequentially comprises a first step side 7541, a second step side 7542, a third step side 7543, a fourth step side 7544 and a fifth step side 7545 along the direction from the rear end to the front end, and the first step side 7541, the second step side 7542, the third step side 7543, the fourth step side 7544 and the fifth step side 7545 are sequentially arranged along the back unlocking direction.

Referring to fig. 7 and 18, when the plunger boss 33 is placed on the first step face 431, the first step side 7541 is located on the side of the plunger boss 33 facing away from the unlocking direction, and the circumferential angle between the first step side 7541 and the plunger boss 33 is also 25 °; when the plunger boss 33 is placed on the second step surface 432, the second step side 7542 is located on the side of the plunger boss 33 facing away from the unlocking direction, and the circumferential angle between the second step side 7542 and the plunger boss 33 is also 25 °; when the plunger boss 33 is placed on the third step surface 433, the third step side 7543 is located on the side of the plunger boss 33 facing away from the unlocking direction, and the circumferential angle between the third step side 7543 and the plunger boss 33 is also 25 °; when plunger boss 33 is placed on fourth stepped surface 434, fourth stepped side 7544 is located on the side of plunger boss 33 facing away from the unlocking direction, and the circumferential angle between fourth stepped side 7544 and plunger boss 33 is also 25 °; when the plunger boss 33 is placed on the fifth stepped surface 435, the fifth stepped side 7545 is located on the side of the plunger boss 33 facing away from the unlocking direction, and the circumferential angle between the fifth stepped side 7545 and the plunger boss 33 is also 25 °.

Referring to fig. 18, the retainer tube housing 75 is further provided with a structural collar 755 at the outer edge of the front end thereof. The structure convex ring 755 is provided with a plunger convex part 33 which is used for leaning against the fifth step side 7545 and passes through the structure notch 7551. After the liquid medicine in the cassette bottle is injected, the plunger convex part 33 is arranged in the structure notch 7551 to realize the circumferential locking of the limiting sleeve.

Referring to fig. 17, the trailing ratchet 74 has a coaxially disposed ratchet through hole 744. The ratchet through hole 744 sequentially includes a ratchet front hole 7441 and a ratchet rear hole 7442 along the front end to rear end direction, and the aperture of the ratchet front hole 7441 is larger than that of the ratchet rear hole 7442. When the rear end portion of the stopper tube 75 is inserted into the ratchet through hole 744 of the rear ratchet 74, the rear end of the transition tube portion 752 abuts on the stepped surface at the junction of the ratchet front hole 7441 and the ratchet rear hole 7442.

Referring to fig. 19, the rear ratchet 74 is provided with two axially arranged third locking grooves 745 uniformly circumferentially on the inner wall of the ratchet rear hole 7442. The locking tube portion 753 is provided with two third locking ribs 7532 arranged axially and fitted into the third locking grooves 745 uniformly in the circumferential direction on the outer side wall.

Referring to fig. 13 and 19, the key 72 further has a locking post 726 coaxially disposed on the inner top surface of the receiving cavity 721. The locking studs 726 are circumferentially and uniformly arranged with two axially arranged fourth locking grooves 7261 on the outer side wall. The locking tube portion 753 is circumferentially provided with two fourth locking bars 7533 that correspond one-to-one to the two fourth locking grooves 7261 and can be inserted into the fourth locking grooves 7261 on the inner wall.

Referring to fig. 19, the tail ratchet 74 is further provided with two third elastic catches 746 arranged symmetrically about the axis of the tail ratchet 74 at the upper ratchet portion 742. The locking tube portion 753 is provided with third notches 7534 on an outer side wall, wherein the third notches 7534 correspond to the third elastic buckles 746 one by one and are used for clamping the third elastic buckles 746.

With reference to fig. 1 to 19, the use steps of the driving mechanism of the injection pen are as follows:

1. carrying out an exhaust operation:

rotating the knob in the unlocking direction, and because all parts in the tail cover assembly are circumferentially locked, synchronously rotating the key 72, the tail end ratchet 74 and the limiting pipe sleeve 75 until the first step side 7541 in the limiting pipe sleeve 75 is abutted with the plunger convex part 33, and at the moment, integrally rotating the tail cover assembly for 25 degrees;

the locking hook 47 of the locking sleeve 4 is disengaged from the hook groove 7242, and the push button 72 is moved to the rear end after the locking of the locking hook 47 is lost until it abuts on the restricting convex ring 18 of the housing 1, at which time the driving surface 7241 of the driving convex plate 724 is axially opposed to the guiding surface 461 of the guiding convex 46;

pressing the button 72 in the front end direction, the driving surface 7241 of the driving protrusion 724 abuts on the guiding surface 461 of the guiding protrusion 46 and drives the locking sleeve 4 to rotate 25 ° in the unlocking direction, so that the plunger protrusion 33 of the plunger rod 3 loses the support of the first step surface 431 on the locking sleeve 4, the plunger rod 3 moves in the front end direction under the action of the driving spring 5 until the plunger protrusion 33 is supported by the second step surface 432, and the plunger rod 3 moves 3mm in the front end direction due to the distance between the first step surface 431 and the second step surface 432 being 3mm, for eliminating the fitting gap between the front end of the plunger rod 3 and the cartridge piston;

2. and (3) injection operation:

rotating the knob in the unlocking direction until the first step side 7541 in the limiting sleeve is abutted with the plunger convex part 3333, and at the moment, integrally rotating the tail end assembly for 25 degrees; the locking hook 47 of the locking sleeve 4 is disengaged from the hook groove 7242 of the key 72, and the key 72 moves to the rear end after losing the locking of the locking hook 47 until it abuts on the positioning ring groove 22 of the housing 1, at which time the driving surface 7241 of the driving lug 724 is axially opposite to the guiding surface 461 of the guiding protrusion 46;

pressing the button 72 in the front end direction causes the driving surface 7241 of the driving plate 724 to abut against the guide surface 461 of the guide protrusion 46 and drive the locking sleeve 4 to rotate 25 ° in the unlocking direction, so that the plunger protrusion 33 of the plunger rod 3 loses the support of the second step surface 432, the plunger rod 3 moves in the front end direction under the action of the driving spring 5 until the plunger protrusion 33 is supported by the third step surface 433, and the plunger rod 3 moves 10mm in the front end direction due to the distance between the second step surface 432 and the third step surface 433 being 10 mm;

3. and (5) when the next injection is needed, repeating the step (2) to finish the injection operation.

In the present embodiment, the injection pen driving mechanism can perform 1 air discharging operation and 4 injection operations in total, wherein the number of injection operations can be performed by adjusting the number of step faces on the locking step structure and the number of side edges of the limit step on the limit step structure.

The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims (9)

1. An injection pen driving mechanism, characterized in that: the device comprises a shell (1), a mounting bracket (2) which is arranged on the shell (1) and is locked with the shell (1) in the circumferential direction, a plunger rod (3) which is axially and slidably arranged on the mounting bracket (2), a driving spring (5) which is arranged on the mounting bracket (2) and is used for driving the plunger rod (3), and a locking sleeve (4);

the plunger rod (3) is provided with a plunger convex part (33) on the side wall of the rear end; the mounting bracket (2) is provided with a driving tube part (24) for axially slidably mounting the plunger rod (3), and the driving tube part (24) is provided with a plunger sliding groove (243) for extending the plunger convex part (33) and axially slidably mounting the plunger convex part (33); the locking sleeve (4) is circumferentially and rotatably arranged on the outer side of the driving tube part (24), and the locking sleeve (4) is provided with a locking stepped structure for being abutted by the plunger convex part (33) to restrain the plunger rod (3) from moving towards the injection direction; defining a circumferential direction of an inclination direction of the locking stepped structure in a direction from the front end to the rear end as an unlocking direction; the injection pen driving mechanism is further provided with a tail cap assembly which drives the locking sleeve (4) to rotate towards an unlocking direction so that the plunger convex part (33) moves axially step by step along the locking stepped structure.

2. An injection pen drive mechanism as claimed in claim 1, wherein: the tail cap assembly is rotatably mounted on the housing (1), the formations in the tail cap assembly being configured to be circumferentially locked; the tail cover assembly comprises a key (72) and a tail end spring (73), the key (72) is installed on the shell (1) and is provided with a first station and a second station in the axial direction, and the second station is located behind the first station; the key (72) is circumferentially limited when moving from the second station to the first station; the locking sleeve (4) has a guide surface (461) arranged in the direction of the rear end; the push button (72) has a drive surface (7241) for abutting against the guide surface (461) to drive the locking sleeve (4) to rotate in the unlocking direction.

3. An injection pen drive mechanism as claimed in claim 2, wherein: the locking sleeve (4) is further provided with a locking hook part (47), and the key (72) is provided with a hook groove (7242); the hook groove (7242) is configured to be inserted by the lock hook (47) when the key (72) is in the first position, restricting movement of the key (72) in the axial direction.

4. An injection pen drive mechanism according to claim 3, characterized in that: the push button (72) has a drive cam (724) extending in the direction of the locking sleeve (4), the drive surface (7241) and the hook groove (7242) being provided on the drive cam (724).

5. An injection pen drive mechanism as claimed in claim 2, wherein: the tail cover assembly comprises a limiting pipe sleeve (75) sleeved on the outer side of the plunger rod (3), and the limiting pipe sleeve (75) is provided with a limiting stepped structure for abutting the plunger convex part (33); the limiting step structure is positioned on one side, back to the locking step convex part, of the plunger convex part (33); the stopper step structure is configured such that the drive surface (7241) is directly opposed to the guide surface (461) when the plunger protrusion (33) abuts on the stopper step structure.

6. An injection pen drive mechanism as claimed in claim 2, wherein: the tail cover assembly comprises a tail end ratchet wheel (74), the tail end ratchet wheel (74) and the fixed ratchet wheel (6) are connected through a ratchet structure, so that the fixed ratchet wheel (6) can rotate relative to the tail end ratchet wheel (74) in an unlocking direction, and the fixed ratchet wheel (6) is limited to rotate relative to the tail end ratchet wheel (74) in a back unlocking direction; the tail end spring (73) drives the tail end ratchet wheel (74) to have a tendency of always abutting against the end of the fixed ratchet wheel (6) section.

7. An injection pen drive mechanism according to claim 6, characterized in that: the fixed ratchet wheel (6) is axially mounted on the shell (1) in a sliding manner; the locking sleeve (4) and the fixed ratchet (6) are also connected by a ratchet structure, such that the locking sleeve (4) can rotate relative to the fixed ratchet (6) in an unlocking direction and the locking sleeve (4) is restricted from rotating relative to the fixed ratchet (6) in a direction facing away from the unlocking direction; the tail end spring (73) drives the fixed ratchet wheel (6) to have a tendency of always abutting against the end of the locking sleeve (4).

8. An injection pen drive mechanism as claimed in claim 2, wherein: the tail cover assembly further comprises a rotary cover (71) which is circumferentially and rotatably arranged at the tail end of the shell (1).

9. An injection pen drive mechanism as claimed in claim 1, wherein: the number of the plunger protrusions (33) on the plunger rod (3) is two, and the two plunger protrusions (33) are arranged symmetrically with respect to the axis of the plunger rod (3).

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