Positive and negative rotation adjusting mechanism for injector and injection pen

Abstract

The invention belongs to the technical field of injectors, and particularly relates to a forward and reverse rotation adjusting mechanism for an injector and an injection pen. The forward and reverse rotation adjusting mechanism for the injector comprises a rotary drum gear, and ratchets are arranged on the end wall of the rotary drum gear; the dosage knob is rotationally arranged at the end part of the pen body; the push rod rotating cylinder and the rotating cylinder gear are coaxially arranged, and the push rod rotating cylinder is suitable for axially moving relative to the pen body; the drum upper gear is arranged in the dosage knob, sleeves the outer wall of the push rod drum and is meshed with the drum gear; when the dosage knob rotates in the forward direction, the gear on the rotary drum is driven to rotate in the forward direction relative to the rotary drum gear so as to pressurize the coil spring in the pen body. When the dosage knob rotates reversely, the drum upper gear is pushed by the dosage knob to move in the direction away from the drum gear and is disengaged from the ratchet, so that the drum upper gear rotates reversely relative to the drum gear; through cooperation of the drum gear, the drum upper gear and the dosage knob, forward and reverse rotation adjustment of the drum gear is achieved, and the size of the interior of the pen body is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of syringes, and in particular relates to a forward and reverse rotation regulating mechanism for syringes and an injection pen. Background Art

[0002] In the related art, a Chinese patent application with publication number CN201324413Y discloses a quantitatively adjustable pen-type syringe, which includes a fixed tube, a pusher head, a sleeve, a clutch sleeve, rotating teeth, a screw, a transmission tube, a stop ring, a fixed ring, a coil, a transfer gear cylinder, a transmission gear cylinder, a sleeve, etc. It adjusts the pre-compression dose during injection by rotating the end of the coil. In the process of pressing the coil inward, the coil drives the transfer gear cylinder, the transmission gear cylinder, the transmission tube, the rotating teeth and the screw to rotate, thereby pushing the screw forward relative to the sleeve and injecting the injection placed in the fixed tube into the human body in a quantitative manner; it is equipped with a back-stop mechanism, so that even if the coil is adjusted backward during the next injection, the pusher head will not retreat.

[0003] The aforementioned adjustable dosage pen-type injector utilizes a rotary tube to drive the intermediate gear cylinder, transmission gear cylinder, transmission tube, rotating gear, and screw, thereby advancing the screw relative to the housing. However, the aforementioned adjustable dosage pen-type injector requires multiple ratchet mechanisms to achieve forward and reverse rotation, resulting in a complex structure. Furthermore, this structure results in a bulky forward and reverse adjustment mechanism, requiring a larger space within the injector.

[0004] Therefore, how to solve the above-mentioned defects is a technical problem that needs to be solved urgently in this field.

[0005] It should be noted that the above information disclosed in this background technology section is only used to understand the background technology of the present application concept, and therefore, the above description is not considered to constitute information of related technology. Summary of the Invention

[0006] The embodiments of the present disclosure at least provide a forward and reverse rotation adjustment mechanism for a syringe and an injection pen.

[0007] In a first aspect, an embodiment of the present disclosure provides a forward and reverse rotation adjustment mechanism for a syringe, comprising: The drum gear is fixed in the pen body, and the end wall of the drum gear is provided with a ratchet; The dosage knob is rotatably mounted on the end of the pen body; the push rod drum is coaxially mounted with the drum gear and is adapted to move axially relative to the pen body; The upper gear of the drum is arranged in the dosage knob, sleeved on the outer wall of the push rod drum, and meshed with the drum gear; When the dose knob is rotated in the forward direction, the gear on the drive drum rotates in the forward direction relative to the drum gear, thereby driving the push rod drum to rotate and wind the coil spring in the pen body; When the dose knob is rotated in the reverse direction, the gear on the drum is pushed by the dose knob to move in the direction away from the drum gear and disengages from the ratchet to make the gear on the drum rotate in the reverse direction relative to the drum gear.

[0008] In an optional embodiment, two annular spring plates are provided on the peripheral wall of the upper gear of the rotating drum, one end of each of the annular spring plates extends circumferentially in the same direction along the upper gear of the rotating drum, and the other end of each of the annular spring plates extends obliquely toward the rotating drum gear and engages with corresponding ratchet teeth; When the dosage knob is rotated in the forward direction, the annular spring hits each ratchet tooth in sequence to produce a sound.

[0009] In an optional embodiment, the inner wall of the dose knob is provided with two push blocks, one push block corresponds to one annular spring piece, and the annular spring piece overlaps the corresponding push block; When the dosage knob rotates in the reverse direction, the push block pushes the annular spring piece to elastically deform in a direction away from the drum gear, and the annular spring piece is disengaged from the ratchet gear. So that the gear on the drum rotates in the opposite direction relative to the drum gear.

[0010] In an optional embodiment, the gear on the rotating drum includes: The main body is annular and sleeved on the outer wall of the push rod rotating cylinder; a first flange, wherein the two first flanges are symmetrically arranged on the outer side wall of the body; a second flange, wherein the two second flanges are symmetrically arranged on the outer side wall of the body and located between the two first flanges; A groove is provided between the first flange side wall and the second flange side wall; The annular elastic sheet extends from the first flange side wall along the circumference of the body.

[0011] In an optional embodiment, the annular spring piece includes a first spring piece and a second spring piece, the first spring piece is arranged on the side wall of the first flange, and the second spring piece is arranged at an end of the first spring piece and has an included angle relative to the first spring piece; The second elastic piece is engaged with the ratchet.

[0012] In an optional embodiment, a limit plate is provided in the dose knob, the limit plate is sleeved on the outer wall of the push rod drum and abuts against the side wall of the gear on the drum away from the drum gear; Two support blocks are provided on the inner wall of the dosage knob. The support block is provided between the two push blocks, and the support block and the limiting plate are respectively provided on both sides of the body.

[0013] In an optional embodiment, the inner wall of the dose knob is further provided with two limit blocks, the limit blocks are located in the groove, and the limit blocks are suitable for sliding in the groove; When the dosage knob rotates forward, the limit block slides to abut against the second flange to push the body to rotate forward synchronously; When the dose knob rotates in the opposite direction, the limit block slides toward the side of the first flange, and the push block first pushes the annular spring sheet to elastically deform until it disengages from the ratchet, and then the limit block abuts against the first flange to push the body to rotate in the opposite direction synchronously.

[0014] In an optional embodiment, a plurality of first racks are evenly distributed circumferentially on the inner wall of the main body; A positioning ring is provided on the outer wall of the push rod rotating cylinder, and a plurality of second racks are symmetrically provided on the outer wall of the positioning ring. The second racks are meshed with the first racks.

[0015] In an optional embodiment, a coil spring bracket is provided on a side of the drum gear away from the upper gear of the drum, and the other end of the coil spring bracket is fixed to the end wall of the scale plate; The coil spring is located in the coil spring bracket, the inner end of the coil spring is fixed to the outer wall of the push rod rotating cylinder, and the outer end of the coil spring is fixed to the inner wall of the coil spring bracket.

[0016] In a second aspect, the present embodiment further provides an injection pen, further comprising a button disposed at the outer end of the push rod barrel, wherein the button can slide axially relative to the dose knob.

[0017] The present invention provides a forward / reverse adjustment mechanism for syringes. Through the coordination of a drum gear, a drum upper gear, and a dosage knob, forward / reverse adjustment is achieved with a single gear mechanism. Compared to conventional syringes that rely on multiple ratchet mechanisms for forward / reverse adjustment, the present invention significantly simplifies the internal structure, reduces the number of parts, and reduces the internal space occupied by the syringe body.

[0018] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description and the drawings.

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited herein and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in related technologies, the following briefly introduces the drawings required for use in the specific embodiments or related technical descriptions. Obviously, the drawings described below are 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.

[0021] Figure 1 An expanded perspective view of a forward and reverse adjustment mechanism for a syringe provided in an embodiment of the present disclosure; Figure 2 A cutaway perspective view of a dose knob provided for an embodiment of the present disclosure; Figure 3 A perspective view of a gear on a rotating drum according to an embodiment of the present disclosure; Figure 4 A perspective view of a push rod according to an embodiment of the present disclosure; Figure 5 A cross-sectional view of a forward and reverse rotation adjustment mechanism for a syringe provided in an embodiment of the present disclosure; Figure 6 Exploded perspective view of the dose knob and drum gear provided for an embodiment of the present disclosure.

[0022] In the picture: 1. Pen body; 10. Button; 2. Drum gear; 21. Coil spring bracket; 22. Ratchet; 3. Dosage knob; 31. Push block; 32. Limit plate; 33. Support block; 34. Limit block; 4. Push rod drum; 41. Positioning ring; 42. Second rack; 5. Gear on the rotating drum; 51. Annular spring piece; 511. First section of spring piece; 512. Second section of spring piece; 52. First rack; 53. Main body; 54. First flange; 55. Second flange; 56. Groove. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0024] In this document, when it is mentioned that a first component is located on a second component, this may mean that the first component may be directly formed on the second component, or that a third component may be interposed between the first component and the second component. In addition, in the drawings, the thickness of components may be exaggerated or reduced in order to effectively describe technical content.

[0025] Herein, example embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as "at least one of..." when following a list of elements modify the entire list of elements, rather than modifying individual elements in the list. For example, the expression "at least one of a, b, and c" should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0026] The terms used herein are only used to describe specific exemplary configurations and are not intended to be limiting. As used herein, the singular articles "a", "an" and "the" may also be intended to include plural forms, unless otherwise clearly indicated herein. The terms "comprise", "include" and "have" are inclusive and therefore specify the presence of features, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or combinations thereof. The method steps, processes and operations described herein should not be interpreted as necessarily requiring them to be performed in the particular order discussed or shown, unless specifically identified as an execution order. Additional or alternative steps may be adopted.

[0027] As used herein, the phrases "in one embodiment," "according to one embodiment," "in some embodiments," and the like generally refer to the fact that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure. Thus, a particular feature, structure, or characteristic may be included in more than one embodiment of the present disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms "example," "exemplary," and the like are used to "serve as an example, instance, or illustration." Any implementation, aspect, or design described herein as "example" or "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations, aspects, or designs. Instead, the use of the terms "example," "exemplary," and the like is intended to present concepts in a concrete manner.

[0028] After research, it was found that the Chinese patent application with the relevant technical announcement number CN201324413Y disclosed a quantitatively adjustable pen-type syringe, which includes a fixed tube, a pusher head, a sleeve, a clutch sleeve, a rotating gear, a screw, a transmission tube, a stop ring, a fixed ring, a coil, a transfer gear cylinder, a transmission gear cylinder, a sleeve, etc. It adjusts the pre-compression dose during injection by rotating the end of the coil. In the process of pressing the coil inward, the coil drives the transfer gear cylinder, the transmission gear cylinder, the transmission tube, the rotating gear and the screw to rotate, thereby pushing the screw forward relative to the sleeve and injecting the injection placed in the fixed tube into the human body in a quantitative manner; it is equipped with a back-off mechanism, so that even if the coil is adjusted backward during the next injection, the pusher head will not retreat.

[0029] The aforementioned adjustable-quantity pen-type injector actually rotates the intermediate gear cylinder, the transmission gear cylinder, the transmission tube, the rotating gear, and the screw, thereby advancing the screw relative to the sleeve. However, the aforementioned adjustable-quantity pen-type injector has the following disadvantages: 1. The forward and reverse adjustment mechanism is large in size, requiring a larger accommodation space in the syringe, which limits the portability of the design.

[0030] 2. Multiple sets of ratchet structures are required to achieve forward and reverse rotation, which has a complex structure, a large number of parts, and a high assembly error rate, affecting dosage accuracy.

[0031] Therefore, how to solve the above-mentioned defects is a technical problem that needs to be solved urgently in this field.

[0032] The defects in the above solutions and the causes of their occurrence are the results obtained by the inventors after practice and careful research. Therefore, the process of discovering the above problems and the solutions proposed by the present disclosure in this article should be the contributions made by the inventors to the present disclosure during the disclosure process.

[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0034] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0035] like Figures 1 to 6As shown, at least one embodiment provides a forward / reverse rotation adjustment mechanism for a syringe, comprising: a drum gear 2 fixed within a pen body 1; a ratchet 22 provided on the end wall of the drum gear 2, the ratchet 22 facing an annular spring 51; a dose knob 3 rotatably mounted at the end of the pen body 1, configured to drive a drum gear 5 in forward and reverse rotation; forward rotation of the drum gear 5 drives a push rod drum 4 to rotate, thereby winding a coil spring within the pen body 1 and adjusting the syringe's injection dose; the inner wall of the dose knob 3 mates with the drum gear 5, enabling the dose knob 3 to rotate circumferentially relative to the drum gear 5; forward rotation of the dose knob 3 drives the drum gear 5 to rotate in a synchronous forward direction; reverse rotation of the dose knob 3 causes the dose knob 3 to rotate idly relative to the drum gear 5 until the push block 31 pushes against the annular spring 51, causing it to deform, and the dose knob 3 drives the drum gear 5 to rotate in a synchronous reverse direction. The push rod drum 4 is coaxially arranged with the upper drum gear 5 and is adapted for axial movement relative to the pen body 1. The upper drum gear 5 is sleeved on the outer wall of the push rod drum 4 and meshes with the drum gear 2. When the upper drum gear 5 rotates forward, the annular spring 51 sequentially abuts the ratchet 22, preventing the upper drum gear 5 from rotating in the reverse direction. When the dose knob 3 rotates forward, the upper drum gear 5 rotates forward relative to the drum gear 2, thereby pressurizing the coil spring within the pen body 1. When the dose knob 3 rotates in the reverse direction, the annular spring 51 is elastically deformed by the push block 31, disengaging the annular spring 51 from the ratchet 22. The upper drum gear 5 rotates in the reverse direction relative to the ratchet 22, releasing the coil spring and reducing the injection dose. The coordination of the drum gear 2, the upper drum gear 5, and the dose knob 3 allows for forward and reverse adjustment using a single gear mechanism. Compared with traditional syringes that rely on multiple sets of ratchet structures to achieve forward and reverse adjustment, the present invention significantly simplifies the internal structure, reduces the number of parts, and compresses the internal space occupied by the pen body 1.

[0036] Reference Attachment Figure 3Two annular spring pieces 51 are provided on the sidewalls of the upper drum gear 5. One end of each annular spring piece 51 extends circumferentially in the same direction along the upper drum gear 5, and the other end of each annular spring piece 51 extends obliquely toward the ratchet wheels 22 and meshes with each ratchet wheel 22. When the dose knob 3 is rotated in the forward direction, the annular spring pieces 51 sequentially strike the ratchet wheels 22 to produce a sound. The sound here refers to the sound produced by the annular spring pieces 51 striking the ratchet wheels 22, alerting the user. The annular spring piece 51 comprises a first section 511 and a second section 512. The first section 511 is provided on the sidewalls of the first flange 54. A gap is provided between the inner wall of the first section 511 and the outer wall of the body 53. The first section 511 and the second section 512 are integrally provided. The second section 512 is provided at the end of the first section 511 and is angled relative to the first section 511. The second section 512 meshes with the ratchet wheels 22. The arrangement of the first and second segments 511, 512, ensures controllable deformation and durability of the annular spring 51. The ratchet 22 and the annular spring 51 are aligned at the same angle. When the dose knob 3 stops rotating, the ratchet 22 prevents the gear 5 on the drum from rotating in the opposite direction, ensuring accurate adjustment of the syringe dose.

[0037] Reference Attachment Figure 2 The dose knob 3 is provided with two push blocks 31 on its inner wall, each corresponding to an annular spring piece 51. The annular spring piece 51 overlaps the corresponding push block 31. When the dose knob 3 is rotated in the reverse direction, the dose knob 3 rotates relative to the drum gear 5. The push block 31 abuts the annular spring piece 51, pushing against the annular spring piece 51 and causing it to elastically deform, disengaging the annular spring piece 51 from the ratchet 22. At this point, the dose knob 3 drives the drum gear 5 to rotate in the reverse direction, causing the drum gear 5 to rotate in the reverse direction relative to the ratchet 22. The push block 31 is located between the annular spring piece 51 and the drum gear 2.

[0038] Reference Attachment Figure 3 The upper drum gear 5 comprises a body 53, which is annular and sleeved onto the outer wall of the push rod drum 4. When the dose knob 3 rotates forward, it drives the body 53 to rotate synchronously, which in turn drives the push rod drum 4 to rotate synchronously. A first flange 54 is symmetrically positioned on the outer wall of the body 53. A second flange 55 is symmetrically positioned on the outer wall of the body 53 and located between the two first flanges 54. A groove 56 is defined between the sidewalls of the first and second flanges 54, 55. The stopper 34 on the inner wall of the dose knob slides within the groove. The annular spring 51 extends from the sidewall of the first flange 54 along the circumference of the body 53.

[0039] Reference Attachment Figure 2A limit plate 32 is provided in the dose knob 3, and the limit plate 32 is sleeved on the outer wall of the push rod drum 4 and abuts against the side wall of the drum upper gear 5 away from the drum gear 2; two support blocks 33 are provided on the inner wall of the dose knob 3, and the support block 33 is provided between the two push blocks 31, and the support block 33 and the limit plate 32 are respectively provided on both sides of the body 53. The inner wall of the dose knob 3 is further provided with two limit blocks 34, which are located in the groove 56 and are suitable for sliding in the groove 56; wherein, when the dose knob 3 rotates forward, the limit block 34 slides to abut against the second flange 55 to push the body 53 to rotate forward synchronously; when the dose knob 3 rotates reversely, the limit block 34 slides to the side of the first flange 54, and the push block 31 first pushes the annular spring piece 51 to elastically deform and disengage from the ratchet 22, and the limit block 34 then abuts against the first flange 54 to push the body 53 to rotate reversely synchronously. Figure 4 and Figure 6 The inner wall of the upper drum gear 5 is uniformly distributed with a plurality of first racks 52. The outer wall of the push rod drum 4 is provided with a positioning ring 41. A plurality of second racks 42 are symmetrically arranged on the outer wall of the positioning ring 41. The second racks 42 mesh with the first racks 52. The cooperation between the first racks 52 and the second racks 42 prevents the upper drum gear 5 from rotating relative to the push rod drum 4. The cooperation between the first racks 52 and the second racks 42 prevents the upper drum gear 5 from rotating synchronously with the drum gear 2. The axial thickness of the positioning ring 41 is greater than the axial thickness of the upper drum gear 5.

[0040] Reference Attachment Figure 5 A coil spring bracket 21 is provided on the side of the drum gear 2 away from the drum upper gear 5, and the other end of the coil spring bracket 21 is fixed to the end wall of the dial; the coil spring is located in the coil spring bracket 21, the inner end of the coil spring is fixed to the outer wall of the push rod drum 4, and the outer end of the coil spring is fixed to the inner wall of the coil spring bracket 21.

[0041] Reference Attachment Figure 1 At least one embodiment provides an injection pen, further comprising a button 10 , which is disposed at the outer end of the push rod drum 4 and can slide axially relative to the dose knob 3 .

[0042] When the button 10 is pushed toward the pen body 1 , the button 10 pushes the push rod cylinder 4 to move axially toward the inside of the pen body 1 to activate the coil spring.

[0043] Here’s how it works: Before injecting medication, the dose knob 3 is rotated forward, which drives the gear 5 on the drum to rotate synchronously. This, in turn, drives the push rod drum 4 to rotate synchronously, compressing the torsion spring. After the dial has rotated to the desired scale, the button 10 is pressed. This activates the coil spring, which in turn drives the transmission connecting rod within the pen body 1, driving the refill inside the pen body 1 to inject the dosed medication. As the dose knob 3 rotates forward, the gear 5 on the drum rotates relative to the pen body 1, causing the annular spring 51 to contact the ratchet 22 in turn, preventing the gear 5 on the drum from retracting.

[0044] If the dose knob 3 is rotated excessively, that is, the dial rotates beyond the required scale, the dose knob 3 is rotated in the reverse direction. The dose knob 3 rotates in the opposite direction relative to the drum gear 5, and the push block 31 pushes the annular spring 51 to deform, causing the annular spring 51 to disengage from the ratchet 22. At this time, the reverse rotation of the dose knob 3 drives the drum gear 5 to rotate in the reverse direction synchronously, releasing the elastic force applied to the torsion spring until the dial reaches the preset scale. Forward rotation of the dose knob increases the injection dose of the syringe, while reverse rotation decreases the injection dose of the syringe.

[0045] In the description of the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0046] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, terms such as "first", "second" and other numerical terms do not imply an order or sequence when used herein unless expressly indicated above. Therefore, without departing from the teachings of the example embodiments, the first element, component, region, layer or section discussed above may be referred to as a second element, component, region, layer or section.

[0047] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A forward and reverse adjustment mechanism for a syringe, characterized in that: include: A rotating drum gear (2) is fixed in the pen body (1), and a ratchet (22) is provided on the end wall of the rotating drum gear (2); a dosage knob (3) rotatably arranged at the end of the pen body (1); a push rod drum (4) coaxially arranged with the drum gear (2) and adapted to move axially relative to the pen body (1); The upper gear (5) of the rotary drum is arranged in the dosage knob (3), is sleeved on the outer wall of the push rod rotary drum (4), and is meshed with the rotary drum gear (2); When the dosage knob (3) is rotated in the forward direction, the gear (5) on the driving drum rotates in the forward direction relative to the drum gear (2), thereby driving the push rod drum (4) to rotate to wind the coil spring in the pen body (1); When the dose knob (3) is rotated in the reverse direction, the upper gear (5) of the drum is pushed by the dose knob (3) to move in a direction away from the drum gear (2) and disengages from the ratchet (22) so that the upper gear (5) of the drum rotates in the reverse direction relative to the drum gear (2).

2. The forward and reverse rotation adjustment mechanism for a syringe according to claim 1, wherein: Two annular spring pieces (51) are provided on the peripheral wall of the upper gear (5) of the rotating drum. One end of each annular spring piece (51) extends circumferentially in the same direction along the upper gear (5) of the rotating drum, and the other end of each annular spring piece (51) extends obliquely toward the rotating drum gear (2) and meshes with corresponding ratchet teeth (22). When the dosage knob (3) is rotated in the forward direction, the two annular springs (51) sequentially strike the ratchet teeth (22) to produce a sound.

3. The forward and reverse rotation adjustment mechanism for a syringe according to claim 2, wherein: Two push blocks (31) are provided on the inner wall of the dosage knob (3), one push block (31) corresponds to one annular spring piece (51), and the annular spring piece (51) is overlapped on the corresponding push block (31); When the dosage knob (3) rotates in the reverse direction, the push block (31) pushes the annular spring piece (51) to elastically deform in a direction away from the drum gear (2), and the annular spring piece (51) is disengaged from the ratchet (22). This causes the upper gear (5) of the drum to rotate in the opposite direction relative to the drum gear (2).

4. The forward and reverse rotation adjustment mechanism for a syringe according to claim 3, wherein: The gear (5) on the rotating drum comprises: The body (53) is annular and sleeved on the outer wall of the push rod rotating cylinder; A first flange (54), wherein the two first flanges (54) are symmetrically arranged on the outer side wall of the body (53); a second flange (55), wherein the two second flanges (55) are symmetrically arranged on the outer side wall of the body (53) and located between the two first flanges (54); A groove (56) is provided between the side wall of the first flange (54) and the side wall of the second flange (55); The annular elastic sheet (51) extends from the side wall of the first flange (54) along the circumference of the body (53).

5. The forward and reverse rotation adjustment mechanism for a syringe according to claim 4, characterized in that: The annular spring piece (51) comprises a first spring piece (511) and a second spring piece (512), wherein the first spring piece (511) is arranged on the side wall of the first flange (54), and the second spring piece (512) is arranged at the end of the first spring piece (511) and is provided with an angle relative to the first spring piece (511); The second elastic piece (512) is engaged with the ratchet (22).

6. The forward and reverse rotation adjustment mechanism for a syringe according to claim 4, characterized in that: A limit plate (32) is provided in the dosage knob (3), and the limit plate (32) is sleeved on the outer wall of the push rod drum (4) and abuts against the side wall of the drum upper gear (5) away from the drum gear (2); Two support blocks (33) are provided on the inner wall of the dosage knob (3), the support block (33) is arranged between the two push blocks (31), and the support block (33) and the limiting plate (32) are respectively arranged on both sides of the body (53).

7. The forward and reverse rotation adjustment mechanism for a syringe according to claim 6, characterized in that: The inner wall of the dosage knob (3) is further provided with two limit blocks (34), the limit blocks (34) are located in the groove (56), and the limit blocks (34) are suitable for sliding in the groove (56); When the dosage knob (3) rotates forward, the limit block (34) slides to abut against the second flange (55), thereby pushing the body (53) to rotate forward synchronously; When the dosage knob (3) is rotated in the reverse direction, the limit block (34) slides toward the side of the first flange (54), and the push block (31) first pushes the annular spring sheet (51) to elastically deform until it is disengaged from the ratchet (22), and the limit block (34) then abuts against the first flange (54) to push the body (53) to rotate in the reverse direction synchronously.

8. The forward and reverse rotation adjustment mechanism for a syringe according to claim 2, wherein: A plurality of first racks (52) are evenly distributed along the circumference of the inner wall of the body; A positioning ring (41) is provided on the outer wall of the push rod rotating cylinder (4), and a plurality of second racks (42) are symmetrically provided on the outer wall of the positioning ring (41), and the second racks (42) and the first racks (52) are meshed with each other.

9. The forward and reverse rotation adjustment mechanism for a syringe according to claim 1, wherein: A coil spring bracket (21) is provided on a side of the drum gear (2) away from the drum upper gear (5), and the other end of the coil spring bracket (21) is fixed to the end wall of the scale plate; The coil spring is located in the coil spring bracket (21), the inner end of the coil spring is fixed to the outer wall of the push rod rotating cylinder (4), and the outer end of the coil spring is fixed to the inner wall of the coil spring bracket (21).

10. An injection pen, characterized in that: include: The forward and reverse rotation adjustment mechanism for a syringe according to any one of claims 1 to 9, further comprising a button (10) which is arranged at the outer end of the push rod cylinder (4) and can slide axially relative to the dose knob (3).

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