CN215995142U - Injection mechanism - Google Patents

Abstract

The application relates to an injection mechanism, which comprises a mounting bracket, a plunger rod, a driving spring and a locking sleeve, wherein the plunger rod is axially slidably mounted on the mounting bracket, the driving spring is mounted on the mounting bracket and is used for driving the plunger rod, and the locking sleeve is positioned outside the plunger rod and is circumferentially and rotatably mounted on the mounting bracket; the plunger rod is provided with a plunger convex part; the locking sleeve has a locking step structure for abutment by the plunger boss to restrain movement of the plunger rod in the injection direction. The present application has the effect that the fluctuation of the driving force is small and the injection speed is stable when the plunger rod moves in the injection direction.

Description

Injection mechanism

Technical Field

The present application relates to the field of injection pens, and more particularly, to an injection mechanism.

Background

A multi-injection medicine injection device is a medicine injection device capable of injecting a liquid medicine in a medicine tube into a patient in several divided injections. Since the multi-injection medicine injection device can be used several times, the requirements of patients are more satisfied. The existing injection pen for multiple injections is internally provided with an injection mechanism, and during injection, the injection 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.

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 mechanism at the time of injection is unstable.

SUMMERY OF THE UTILITY MODEL

In order to minimize the pressure fluctuations exerted on the cartridge piston during injection, the present application provides an injection mechanism.

The application provides an injection mechanism, adopts following technical scheme:

an injection mechanism comprises a mounting bracket, a plunger rod axially slidably mounted on the mounting bracket, a drive spring mounted on the mounting bracket and used for driving the plunger rod, and a locking sleeve positioned outside the plunger rod and circumferentially rotatably mounted on the mounting bracket; the plunger rod is provided with a plunger convex part; the locking sleeve has a locking step structure for abutment by the plunger boss to restrain movement of the plunger rod in the injection direction; wherein a circumferential direction of an oblique direction of the locking stepped structure in a direction from the front end to the rear end is defined as an unlocking direction.

By adopting the technical scheme, the injection mechanism rotates the locking sleeve towards the unlocking direction when in use, so that the restraint of the locking stepped structure in the locking sleeve on the plunger convex part disappears, the plunger rod moves towards the injection direction for a certain distance, and the distance can be controlled by the distance between two adjacent stepped surfaces in the locking stepped structure.

The injection mechanism does not transmit the force of a user through a built-in transmission structure, but presses the plunger rod through the driving spring, so that the fluctuation of the driving force when the plunger rod moves towards the injection direction is small, the speed change of the injection pen with the injection mechanism when liquid medicine is input into a patient body is small, the liquid medicine amount input into the patient body in unit time is stable, and the experience feeling of the patient when the liquid medicine is injected is improved.

Optionally, the locking stepped structure includes a stepped convex portion arranged on the inner wall of the locking sleeve, the stepped convex portion has at least two stepped surfaces for the plunger convex portion to abut against, and adjacent to each other, an injection stroke is formed between the stepped surfaces.

Optionally, the locking stepped structure includes a stepped hole that runs through the inner and outer surfaces of the locking sleeve, the stepped hole has at least two stepped surfaces for the plunger convex part to abut against, and adjacent to each other, an injection stroke is formed between the stepped surfaces.

Optionally, the number of the step surfaces in the locking stepped structure is not less than three, and the first injection stroke of the stepped convex part along the direction from the rear end to the front end is an exhaust stroke.

Through adopting above-mentioned technical scheme for the medicine injection device of above-mentioned many times injection can carry out the exhaust operation at the in-process of first injection, also is the empty injection when the medicine injection device of above-mentioned many times injection is first injection, has eliminated the clearance volume between plunger rod tip and the cassette bottle piston, makes the liquid medicine volume of output can reach standard in next injection.

Optionally, the mounting bracket includes a driving tube portion for supplying the driving tube portion to be mounted and the rear end of the driving tube portion is sealed, the driving tube portion has a driving tube cavity for supplying the plunger rod to be axially slidably mounted, and the driving tube portion is further provided with a plunger sliding groove for supplying the plunger convex portion to extend out and for supplying the plunger convex portion to axially slide.

Through adopting above-mentioned technical scheme, disclosed the axial sliding structure of plunger rod on the installing support. The plunger sliding groove is formed in the mounting support, so that the plunger convex part can extend out of the driving tube cavity, the plunger convex part and the locking sleeve are matched, the plunger sliding groove can guide axial sliding of the plunger convex part, and the axial sliding of the plunger rod on the mounting support is more stable.

Optionally, the driving tube part is provided with a guide ring part arranged circumferentially, and the guide ring part is provided with a guide notch which is opposite to the plunger sliding groove and used for the plunger convex part to pass through; the locking sleeve comprises a front tube body part which is sleeved outside the guide ring part and matched with the guide ring part.

Through adopting above-mentioned technical scheme, guide ring portion can support on the inner wall of preceding body portion, has reduced the probability that locking sleeve takes place to deflect the dislocation on the installing support.

Optionally, the outer side wall of the drive tube part is provided with a reinforcing rib plate which is connected with the guide ring part and is arranged axially.

Through adopting above-mentioned technical scheme, the design of reinforcing floor has helped improving the structural strength of guide ring portion on the drive tube portion, has reduced the guide ring portion and has taken place the probability of buckling the damage.

Optionally, the driving tube part is coaxially provided with spring insertion posts for sleeving the driving spring on the rear end surface of the driving tube cavity; the plunger rod has a spring groove with a rear end opening and for insertion of the drive spring.

By adopting the technical scheme, the driving spring is positioned in the spring groove of the plunger rod, and the spring insertion column is inserted into the driving spring, so that the driving force applied to the plunger rod by the driving spring is in the axial direction, namely the moving direction of the plunger rod on the mounting bracket is kept in the axial direction.

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

Through adopting above-mentioned technical scheme, the design of two plunger convex parts on the plunger rod for need two plunger spouts on the drive tube portion, need possess two respectively with two locking stair structure of plunger convex part one-to-one on the locking sleeve, help making above-mentioned injection mechanism more stable at the in-process of operation.

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

1. the injection mechanism presses the plunger rod through the driving spring, so that the driving force is kept constant when the plunger rod moves towards the injection direction, the speed of the injection pen with the injection mechanism is kept constant when liquid medicine is input into a patient, the liquid medicine 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 injection mechanism has an exhaust stroke, so that the injection is performed in an empty state during the first injection, the gap between the end part of the plunger rod and the piston of the cassette bottle is eliminated, and the liquid medicine output in the next injection can reach the standard;

3. the guide ring part can be supported on the inner wall of the front pipe body part, so that the probability of deflection dislocation of the locking sleeve on the mounting bracket is reduced.

Drawings

FIG. 1 is a schematic structural view of example 1.

Fig. 2 is an exploded view of example 1.

Fig. 3 is a schematic view of the cooperation of the mounting bracket, plunger rod and drive spring of example 1.

Fig. 4 is a schematic sectional view of the mounting bracket, the plunger rod and the drive spring in the engaged state in embodiment 1.

Fig. 5 is a schematic view of the internal structure of the locking sleeve in embodiment 1.

FIG. 6 is a schematic structural view of embodiment 2.

Fig. 7 is a schematic view of the internal structure of the locking sleeve in embodiment 2.

Description of reference numerals: 1. mounting a bracket; 11. a mounting seat portion; 111. mounting grooves; 112. installing a notch; 12. a drive tube portion; 121. a drive lumen; 122. a plunger slide groove; 13. inserting a spring into the column; 14. a guide ring portion; 141. a guide notch; 15. a reinforcing rib plate; 2. a plunger rod; 21. a spring slot; 22. a plunger boss; 3. a drive spring; 4. a locking sleeve; 41. a front body portion; 411. slipping slot lacking; 42. a rear body portion; 431. a stepped convex portion; 432. a stepped hole; 434. a first step surface; 435. a second step surface; 436. a third step surface; 437. a fourth step surface; 438. a fifth step surface; 439. a slipping channel; 4391. and (6) sliding and opening.

Detailed Description

The present application is described in further detail below with reference to figures 1-7.

The embodiment of the application discloses an injection mechanism.

In the present application, when the term "front end portion/end" is used, this refers to the portion/end of the injection 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 mechanism or components thereof that is remote from the injection area of the body during injection. And the state of the injection mechanism when not in use is defined as the initial state of the injection mechanism.

Example 1

Referring to fig. 1 and 2, the injection mechanism comprises a mounting bracket 1, a plunger rod 2 axially slidably mounted on the mounting bracket 1, a drive spring 3 mounted on the mounting bracket 1 for driving the plunger rod 2, and a locking sleeve 4 circumferentially rotatably mounted on the mounting bracket 1.

Referring to fig. 3 and 4, the mount bracket 1 is made of plastic, and includes a mount portion 11 and a drive tube portion 12 provided at a rear end surface of the mount portion 11. The mounting seat portion 11 has a hollow tubular structure and has a mounting groove 111 with an open front end.

The drive tube 12 is a hollow tubular structure with a closed rear end and is disposed coaxially with the mounting seat 11. The drive tube portion 12 has an outer diameter smaller than that of the mount portion 11 so that the rear end surface of the mount portion 11 forms a radially arranged stepped surface.

Referring to fig. 4, the driving tube part 12 has a driving lumen 121 communicating with the mounting groove 111 and arranged coaxially with the driving tube part 12. The driving tube part 12 is coaxially disposed with a spring insertion post 13 for receiving the driving spring 3 at a rear end surface of the driving tube cavity 121.

Referring to fig. 4, the plunger rod 2 is mounted coaxially within the drive lumen 121. The plunger rod 2 is coaxially provided with a spring groove 21 at the rear end surface for accommodating the driving spring 3. When the plunger rod 2 is arranged in the drive lumen 121, the front end of the drive spring 3 abuts on the front end surface of the spring groove 21 and the rear end of the drive spring 3 abuts on the rear end surface of the spring groove 21, so that the plunger rod 2 has a tendency to move always in the injection direction.

Referring to fig. 3 and 4, the plunger rod 2 is circumferentially provided with two plunger protrusions 22 at a rear end portion of the outer side wall. The driving lumen 121 is provided with plunger slide grooves 122 which correspond to the two plunger protrusions 22 one by one and are used for allowing the plunger protrusions 22 to slide axially. The mounting bracket 1 is provided with a mounting notch 112 communicating with the mounting groove 111 and used for the plunger convex part 22 to pass through, at the rear end face of the mounting seat part 11, so that the plunger rod 2 can pass through the mounting groove 111 and then be mounted into the driving tube cavity 121 of the driving tube part 12.

Referring to fig. 3 and 5, the locking sleeve 4 is sleeved outside the driving tube part 12 and has 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 5, the drive tube portion 12 is also circumferentially provided with a guide ring portion 14 at an outer side wall of the front end portion. The guide ring portion 14 is supported on the inner surface of the front body portion 41, and the guide ring portion 14 is further provided with a guide notch 141 facing the plunger slide groove 122 for passing the plunger protrusion 22. In order to increase the structural strength of the guide ring section 14 on the drive tube section 12, the drive tube section 12 is also provided with axially arranged reinforcement ribs 15. The reinforcement rib 15 has one end connected to the front end surface of the guide ring portion 14 and the other end connected to the rear end surface of the mount portion 11.

Referring to fig. 3 and 5, the locking sleeve 4 is further provided with two locking step structures on the inner wall, corresponding to the two plunger protrusions 22 one by one, for abutting the plunger protrusions 22 to restrain the plunger rod 2 from moving toward the injection direction. Wherein a circumferential direction of an oblique direction of the locking stepped structure in a direction from the front end to the rear end is defined as an unlocking direction.

The locking step structure is a step protrusion 431 arranged on the inner wall of the locking sleeve 4. The stepped protrusion 431 has five stepped surfaces for abutment of the plunger protrusion 22, and includes a first stepped surface 434, a second stepped surface 435, a third stepped surface 436, a fourth stepped surface 437, and a fifth stepped surface 438 in this order in the rear-end to front-end direction. Wherein, an injection stroke is formed between adjacent stepped surfaces.

In the initial state, i.e. when the multi-shot injection pen is not used, the plunger boss 22 of the plunger rod 2 abuts on the first step surface 434; after the locking sleeve 4 is rotated by a specified angle in the unlocking direction, the plunger boss 22 and the first step surface 434 are disengaged, an injection stroke is formed between the plunger boss 22 and the second step surface 435, and the plunger rod 2 moves in the injection direction until the plunger boss 22 and the second step surface 435 abut under the action of the drive spring 3; when a second injection is to be performed, the locking sleeve 44 needs to be rotated again by a prescribed 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 °.

Wherein, the injection stroke between the first step surface 434 and the second step surface 435 is an exhaust stroke, in this embodiment, the height of the exhaust stroke is 3mm, and the injection stroke between the other two adjacent step surfaces is 10 mm. When the plunger protrusion 22 slides off the fifth step surface 438, the plunger rod 2 will inject the medicine in the cartridge bottle under the action of the driving spring 3 due to the loss of the constraint of the locking step structure in the locking sleeve 4.

Example 2:

the present embodiment is different from embodiment 1 in that: the locking step structure in the locking sleeve 4.

Referring to fig. 6 and 7, in the present embodiment, the locking stepped structure is a stepped hole 432 disposed on the locking sleeve 4. A stepped bore 432 extends through the inner and outer walls of the locking sleeve 4. The stepped hole 432 has five stepped surfaces against which the plunger boss 22 abuts, and includes a first stepped surface 434, a second stepped surface 435, a third stepped surface 436, a fourth stepped surface 437, and a fifth stepped surface 438 in this order in the rear-end to front-end direction. The width of the step surface in the locking step structure is kept consistent, namely, the designated angle of each rotation is also kept consistent. In the present embodiment, the specified angle is 25 °.

An injection stroke is formed between adjacent stepped surfaces. The injection stroke between the first step surface 434 and the second step surface 435 is an exhaust stroke. The height of the exhaust stroke is 3mm, and the injection stroke between the other two adjacent step surfaces is 10 mm. When the plunger protrusion 22 slides off the fifth step surface 438, the plunger rod 2 will inject the medicine in the cartridge bottle under the action of the driving spring 3 due to the loss of the constraint of the locking step structure in the locking sleeve 4.

Referring to fig. 6 and 7, the stepped bore 432 also has a slide passage 439 for the plunger boss 22 to enter and exit the stepped bore 432. A slide passage 439 is connected to an end of the fifth stepped surface 438 facing away from the unlocking direction, and the width of the slide passage 439 is not smaller than the width of the plunger boss 22. Wherein, the sliding channel 439 is axially arranged, and a sliding opening 4391 is formed on the lower end surface of the upper tube body part.

The lock sleeve 4 is provided with a slide notch 411 connected to the slide passage 439 and used for passing the plunger boss 22 at the rear end face of the front tube body 41, so that the plunger boss 22 can be normally installed in the lock sleeve 4.

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 mechanism is characterized by comprising a mounting bracket (1), a plunger rod (2) which is axially slidably mounted on the mounting bracket (1), a drive spring (3) which is mounted on the mounting bracket (1) and used for driving the plunger rod (2), and a locking sleeve (4) which is positioned outside the plunger rod (2) and is circumferentially and rotatably mounted on the mounting bracket (1); the plunger rod (2) is provided with a plunger convex part (22); the locking sleeve (4) has a locking step structure for abutment by the plunger boss (22) to restrain movement of the plunger rod (2) in the injection direction; wherein a circumferential direction of an oblique direction of the locking stepped structure in a direction from the front end to the rear end is defined as an unlocking direction.

2. An injection mechanism according to claim 1, wherein the locking step arrangement comprises a step protrusion (431) arranged on the inner wall of the locking sleeve (4), the step protrusion (431) having at least two step surfaces for abutment by the plunger protrusion (22), an injection stroke being formed between adjacent step surfaces.

3. An injection mechanism according to claim 1, wherein the locking step arrangement comprises a step bore (432) extending through the inner and outer surfaces of the locking sleeve (4), the step bore (432) having at least two step surfaces for abutment by the plunger boss (22), an injection stroke being formed between adjacent step surfaces.

4. An injection mechanism according to claim 2, wherein the number of the step surfaces in the locking step structure is not less than three, and the first injection stroke of the step protrusion (431) in the rear-to-front direction is an exhaust stroke.

5. An injection mechanism according to claim 1, wherein the mounting bracket (1) comprises a drive tube part (12) for mounting the plunger rod (2) and sealing the rear end, the drive tube part (12) has a drive tube cavity (121) for axially slidably mounting the plunger rod (2), and the drive tube part (12) is further provided with a plunger sliding groove (122) for extending the plunger convex part (22) and axially slidably moving the plunger convex part (22).

6. An injection mechanism according to claim 5, wherein said drive tube portion (12) is provided with a circumferentially arranged guide ring portion (14), said guide ring portion (14) having a guide notch (141) directly opposite said plunger runner (122) for passage of said plunger boss (22); the locking sleeve (4) comprises a front tube body part (41) which is sleeved on the outer side of the guide ring part (14) and matched with the guide ring part (14).

7. An injection mechanism according to claim 6, characterized in that the outer side wall of the drive tube part (12) is provided with axially arranged reinforcement ribs (15) connecting the guide ring part (14).

8. An injection mechanism according to claim 5, wherein the driving tube (12) is coaxially provided with a spring insertion column (13) for sleeving the driving spring (3) on the rear end surface of the driving tube cavity (121); the plunger rod (2) is provided with a spring groove (21) which is opened at the rear end and is used for inserting the driving spring (3).

9. An injection mechanism according to claim 1, characterized in that the number of said plunger protrusions (22) on said plunger rod (2) is two, two of said plunger protrusions (22) being arranged symmetrically with respect to the axis of said plunger rod (2).

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