Quantitative dosing prefilled syringe

Abstract

The utility model discloses a quantitative dosing prefilled syringe, which comprises a syringe filled with a preset amount of liquid medicine in advance, and further comprises an injection push rod capable of being inserted into the syringe in an axial moving manner, and a dosage adjusting mechanism capable of being arranged on the syringe in an axial moving manner, the injection push rod is used for pushing liquid medicine in the injection cylinder to flow out, and the dosage adjusting mechanism is used for abutting against the limiting piece so as to limit the pushing stroke of the injection push rod. Thus, when a medical worker needs to inject a small dose at a time, the medical worker only needs to adjust the axial position of the dose adjusting mechanism according to the target axial distance corresponding to the target injection dose, then the injection push rod is pressed to start injection till the limiting piece abuts against the dose adjusting mechanism, and the maximum pushing stroke is achieved; therefore, it can be ensured that the actual injection dosage is equal to the target injection dosage, accurate injection of any dosage can be achieved, the requirement for accurate injection of single-time tiny dosage is met, and the treatment effect of a multi-injection administration mode is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of medical devices, in particular to a pre-filled syringe for quantitative dosing. Background Art

[0002] With the development of the medical industry, the structure of syringes is also being updated.

[0003] At present, prefilled syringes are gradually becoming the mainstream syringes. Prefilled syringes can realize the pre-filling of liquid medicine, that is, the pharmaceutical factory can pre-fill the medicine quantitatively into the syringe. When used clinically, just remove the syringe cap to perform clinical medication. The application areas of prefilled syringes mainly include beauty, vaccines, insulin injections, etc., which are used for subcutaneous injections, intramuscular injections and intravenous injections. Due to the characteristics of prefilling, the secondary pollution and inaccurate dosage caused by the traditional ampoule and vial extraction and dispensing methods are avoided.

[0004] However, although prefilled syringes can achieve precise predetermined dose administration of multiple specifications, due to the influence of cost factors such as production and transportation, prefilled syringes in the prior art can often only achieve precise administration of larger doses, and prefilled syringes of different specifications have different step-by-step administration doses, such as 1ml, 1.5ml, 2ml, 3ml, etc., but the administration doses between the steps, such as 1.2ml, 1.3ml, etc., or the administration doses less than the minimum step, such as 0.8ml, etc., cannot fully inject the prefilled liquid in the syringe, resulting in the inability to achieve precise administration. For some patients, only a single injection of a small dose is required during clinical operation, and the treatment purpose can be achieved through multiple injections. As a result, the prefilled syringes in the prior art cannot achieve precise injection of a single small dose, and medical staff can only rely on experience to control the actual administration amount, resulting in inaccurate and inconsistent doses for each injection, which in turn affects the treatment effect.

[0005] Therefore, how to achieve accurate injection of any dose, meet the needs of accurate injection of a single tiny dose, and ensure the therapeutic effect of multiple injections is a technical problem faced by those skilled in the art. Utility Model Content

[0006] The utility model aims to provide a pre-filled syringe for quantitative administration, which can realize accurate injection of any dose, meet the demand for accurate injection of a single micro-dose, and ensure the therapeutic effect of multiple injection administration.

[0007] In order to solve the above technical problems, the utility model provides a prefilled syringe for quantitative dosing, comprising a syringe barrel prefilled with a preset amount of liquid medicine, and also comprising an injection push rod axially movably inserted in the syringe barrel, and a dose adjustment mechanism axially movably arranged on the syringe barrel, a limit piece is arranged on the injection push rod, the injection push rod is used to push the liquid medicine in the syringe barrel to flow out, and the dose adjustment mechanism is used to form an abutment with the limit piece to limit the pushing stroke of the injection push rod.

[0008] Preferably, the injection push rod comprises a rod body, a piston arranged at the front end of the rod body, and a pressing plate arranged at the rear end of the rod body, and the piston is filled in the injection barrel; the limiter is arranged on the rod body.

[0009] Preferably, the piston is detachably connected to the front end of the rod body.

[0010] Preferably, the limiting member is a limiting ring protruding from the circumference of the rod body.

[0011] Preferably, the dose adjustment mechanism comprises a mounting sleeve fixed on the injection barrel, and an adjusting knob axially movably disposed in the mounting sleeve, wherein the adjusting knob is located inside the stopper so as to abut against the stopper through its outer end surface.

[0012] Preferably, the inner wall surface of the mounting sleeve and the outer wall surface of the adjusting knob form a threaded transmission connection.

[0013] Preferably, the mounting sleeve is installed inside the injection barrel, and the adjusting knob is hollow inside and is sleeved on the injection push rod.

[0014] Preferably, the dose adjustment mechanism further comprises a mounting seat, the bottom surface of the mounting seat is provided with a clamping arm for clamping and fixing the wing at the top end of the injection barrel, and the mounting seat is provided with a mounting through hole for mounting the mounting sleeve.

[0015] Preferably, a plurality of snap-fit ​​grooves are provided on the inner wall of the mounting through hole, and a plurality of snap-fit ​​protrusions are provided on the outer wall of the mounting sleeve, and each of the snap-fit ​​grooves is used to snap-fit ​​with the corresponding snap-fit ​​protrusion.

[0016] Preferably, a reference marking line is provided on the top surface of the mounting seat, and a scale for marking the rotation angle is provided on the circumference of the adjusting knob.

[0017] The quantitative dosing prefilled syringe provided by the utility model mainly includes a syringe barrel, an injection push rod, a limiter and a dose adjustment mechanism. Among them, a preset amount of liquid medicine is pre-filled in the syringe barrel. The injection push rod is inserted in the syringe barrel and can move axially in the syringe barrel to push the liquid medicine in the syringe barrel to flow out of the needle tube to achieve liquid medicine injection. Obviously, there is a preset corresponding relationship between the axial displacement of the injection push rod in the syringe barrel and the injection amount of the liquid medicine. The limiter is arranged on the injection push rod, mainly used to realize the axial movement limit of the injection push rod. The dose adjustment mechanism is arranged on the syringe barrel, and can move axially relative to the syringe barrel to realize the axial position adjustment of the dose adjustment mechanism on the syringe barrel. The dose adjustment mechanism is mainly used to cooperate with the limiter. When the injection push rod is pressed by the medical staff to move axially, the limiter moves synchronously with the injection push rod, and the liquid medicine continues to flow out of the needle tube until the limiter hits the dose adjustment mechanism to form abutment. Due to the abutment of the dose adjustment mechanism, the limiter and the injection push rod cannot continue to move in the same direction, which is equivalent to the injection push rod reaching the current maximum push stroke, and the current actual injection amount corresponds to the current maximum push stroke of the injection push rod. In this way, the quantitative dosing prefilled syringe provided by the utility model, the actual injection amount of the syringe barrel is determined by the axial displacement of the injection push rod, and the maximum axial displacement of the injection push rod is determined by the axial spacing between the dose adjustment mechanism and the limiter. Therefore, when the medical staff needs to inject a small dose in a single time, they only need to adjust the axial position of the dose adjustment mechanism according to the target axial spacing corresponding to the target injection dose, and then press the injection push rod to start injection until the limiter and the dose adjustment mechanism form abutment and reach the maximum push stroke, so as to ensure that the actual injection dose is equal to the target injection dose. If you want to achieve accurate injection of other doses, similarly, you only need to adjust the axial position of the dose adjustment mechanism on the syringe barrel accordingly. Different axial positions represent different axial spacings from the limiter, which in turn determines different injection doses. In summary, the quantitative dosing prefilled syringe provided by the utility model can achieve accurate injection of any dose, meet the needs of accurate injection of a single micro-dose, and ensure the therapeutic effect of multiple injections. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0019] Figure 1 The present invention is a schematic diagram of the overall structure of a specific implementation method provided by the present invention.

[0020] Figure 2 for Figure 1 sectional view of .

[0021] Figure 3 It is a schematic diagram of the specific structure of the injection push rod.

[0022] Figure 4 It is a schematic diagram of the specific structure of the installation sleeve.

[0023] Figure 5 for Figure 4 sectional view of .

[0024] Figure 6 It is a schematic diagram of the specific structure of the adjustment knob.

[0025] Figure 7 Schematic diagram of the specific structure of the mounting base.

[0026] in, Figure 1 — Figure 7 middle:

[0027] Syringe—1, injection plunger—2, dosage adjustment mechanism—3;

[0028] Wings—11;

[0029] Limiting member—21, rod body—22, piston—23, pressing plate—24, connecting head—25;

[0030] Mounting sleeve—31, adjusting knob—32, mounting seat—33;

[0031] Snap-on protrusion—311, internal thread—312;

[0032] Scale—321, external thread—322;

[0033] Clamping arm—331, mounting through hole—332, snap-in groove—333, reference identification line—334. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0035] Please refer to Figure 1 , Figure 2 , Figure 1 This is a schematic diagram of the overall structure of a specific implementation method provided by the utility model. Figure 2 for Figure 1sectional view of .

[0036] In a specific embodiment provided by the utility model, the prefilled syringe for quantitative administration mainly includes a syringe barrel 1 , an injection push rod 2 , a stopper 21 and a dosage adjustment mechanism 3 .

[0037] The syringe 1 is pre-filled with a preset amount of liquid medicine.

[0038] The injection push rod 2 is inserted into the syringe 1 and can move axially in the syringe 1 to push the liquid medicine in the syringe 1 out of the needle tube to achieve liquid medicine injection. Obviously, there is a preset corresponding relationship between the axial displacement of the injection push rod 2 in the syringe 1 and the injection amount of the liquid medicine.

[0039] The limiter 21 is arranged on the injection push rod 2, and is mainly used to realize the axial movement limit of the injection push rod 2. The dose adjustment mechanism 3 is arranged on the injection barrel 1, and can move axially relative to the injection barrel 1 to realize the axial position adjustment of the dose adjustment mechanism 3 on the injection barrel 1.

[0040] The dose adjustment mechanism 3 is mainly used to cooperate with the limit member 21. When the injection push rod 2 is pressed by the medical staff and moves axially, the limit member 21 moves synchronously with the injection push rod 2, and the medicine continues to flow out of the needle tube until the limit member 21 hits the dose adjustment mechanism 3 to form abutment. Due to the abutment of the dose adjustment mechanism 3, the limit member 21 and the injection push rod 2 cannot continue to move in the same direction at this time, which is equivalent to the injection push rod 2 reaching the current maximum pushing stroke. At the same time, the current actual injection amount corresponds to the current maximum pushing stroke of the injection push rod 2.

[0041] In this way, in the prefilled syringe for quantitative dosing provided in this embodiment, the amount of medicine actually injected by the syringe barrel 1 is determined by the axial displacement of the injection push rod 2, and the maximum axial displacement of the injection push rod 2 is determined by the axial spacing between the dose adjustment mechanism 3 and the limiter 21. Therefore, when medical staff need to inject a small dose at a time, they only need to adjust the axial position of the dose adjustment mechanism 3 according to the target axial spacing corresponding to the target injection dose, and then press the injection push rod 2 to start the injection until the limiter 21 and the dose adjustment mechanism 3 form abutment and reach the maximum pushing stroke, thereby ensuring that the actual injection dose is equal to the target injection dose.

[0042] To achieve accurate injection of other doses, similarly, it is only necessary to adjust the axial position of the dose adjustment mechanism 3 on the syringe barrel 1 accordingly. Different axial positions represent different axial distances from the limiter 21, thereby determining different injection doses.

[0043] In summary, the prefilled syringe for quantitative administration provided in this embodiment can realize accurate injection of any dose, meet the demand for accurate injection of a single micro-dose, and ensure the therapeutic effect of multiple injection administration.

[0044] like Figure 3 As shown, Figure 3 It is a schematic diagram of the specific structure of the injection push rod 2.

[0045] In a specific embodiment of the injection push rod 2, the injection push rod 2 mainly includes a rod body 22, a piston 23 and a pressing plate 24. Among them, the rod body 22 is the main structure of the injection push rod 2, which is usually in the shape of a round rod or a square rod and has a preset length. The piston 23 is arranged at the front end of the rod body 22 and is filled in the syringe 1. When the rod body 22 moves axially, it can perform synchronous axial movement in the syringe 1, thereby pushing the liquid medicine in the syringe 1 out of the needle tube to achieve injection. The pressing plate 24 is arranged at the rear end of the rod body 22, usually in the shape of an arc plate, which is convenient for medical staff to press the pressing operation to apply force to the pressing plate 24 to drive the rod body 22 to move axially. Correspondingly, the limiter 21 is specifically arranged on the rod body 22.

[0046] In a specific embodiment of the stopper 21, the stopper 21 is specifically a stopper ring, and is convexly arranged on the circumference of the rod body 22, such as a circular ring, a rectangular ring, etc. In this arrangement, since the end surface area of ​​the adjustment knob 32 in the dose adjustment mechanism 3 is usually larger than the cross-sectional area of ​​the rod body 22 of the injection push rod 2, the larger annular area of ​​the stopper ring can more stably form abutment with the end surface of the adjustment knob 32 in the dose adjustment mechanism 3. Of course, the stopper 21 is not limited to the stopper ring structure, and other structures such as a stopper plate, a stopper block, etc. can also be used.

[0047] Considering that the inner diameters of syringes 1 of different specifications are different, the outer diameter of the piston 23 also needs to change accordingly. In view of this, in this embodiment, the piston 23 and the front end of the rod body 22 are specifically detachably connected. For example, a connector 25 with a thread is provided at the front end of the rod body 22, and then a threaded connection is formed with the inner wall of the piston 23 through the connector 25; or the piston 23 and the front end of the rod body 22 are formed into a pluggable card installation, etc. With such a configuration, pistons 23 of different specifications can be conveniently installed on the rod body 22 of the injection push rod 2 during the product assembly stage. Of course, the piston 23 and the front end of the rod body 22 can also be fixedly connected.

[0048] like Figure 4 , Figure 5 , Figure 6 As shown, Figure 4 Schematic diagram of the specific structure of the installation sleeve 31, Figure 5 for Figure 4 A cross-sectional view of Figure 6FIG. 3 is a schematic diagram of the specific structure of the adjusting knob 32 .

[0049] In a specific embodiment of the dose adjustment mechanism 3, the dose adjustment mechanism 3 mainly includes a mounting sleeve 31 and an adjusting knob 32. The mounting sleeve 31 is specifically fixed on the injection barrel 1 and is mainly used to install the adjusting knob 32. The adjusting knob 32 is movably connected with the mounting sleeve 31 and can move axially in the mounting sleeve 31 to adjust the axial installation position of the adjusting knob 32 relative to the injection barrel 1. At the same time, the adjusting knob 32 is located on the inner side of the stopper 21 on the injection push rod 2, that is, it is closer to the needle tube end of the injection barrel 1 than the stopper 21, so that when the stopper 21 moves axially with the rod body 22 of the injection push rod 2, it can form abutment with the outer end face of the adjusting knob 32. In this way, the axial distance between the outer end face of the adjusting knob 32 and the stopper 21 is the maximum pushing stroke of the injection push rod 2. When the actual injection dose needs to be adjusted, it is only necessary to move the position of the adjusting knob 32 axially outward or inward, and the adjustment method is simple and convenient.

[0050] Furthermore, in order to improve the accuracy of adjusting the axial position of the adjusting knob 32, the present embodiment uses a conversion method of linear motion and rotational motion to achieve the axial position adjustment of the adjusting knob 32. Specifically, in the present embodiment, an internal thread 312 is provided on the inner wall surface of the mounting sleeve 31, and an external thread 322 is provided on the rod of the adjusting knob 32. Through the internal thread 312 and the external thread 322, the mounting sleeve 31 and the adjusting knob 32 form an internal and external nested thread transmission connection. With such arrangement, when the adjusting knob 32 is rotated clockwise, the threaded engagement degree between the adjusting knob 32 and the mounting sleeve 31 deepens, the adjusting knob 32 moves axially inward (the needle tube end), the axial distance between the outer end surface of the adjusting knob 32 and the limiter 21 gradually increases, the maximum pushing stroke of the injection push rod 2 increases accordingly, and the dose value that can be accurately injected becomes larger; conversely, when the adjusting knob 32 is rotated counterclockwise, the threaded engagement degree between the adjusting knob 32 and the mounting sleeve 31 becomes shallower, the adjusting knob 32 moves axially outward, the axial distance between the outer end surface of the adjusting knob 32 and the limiter 21 gradually decreases, the maximum pushing stroke of the injection push rod 2 decreases accordingly, and the dose value that can be accurately injected becomes smaller.

[0051] Of course, the adjusting knob 32 can also directly achieve axial position adjustment by performing axial linear sliding in the mounting sleeve 31 .

[0052] In order to facilitate the assembly of the product and reduce the volume of the product, in this embodiment, the mounting sleeve 31 is specifically installed inside the syringe 1 to form an embedded installation; at the same time, the interior of the adjustment knob 32 is hollow and is sleeved on the injection push rod 2. Of course, it does not affect the pushing stroke of the injection push rod 2 and does not cause motion interference. Specifically, the outer wall of the mounting sleeve 31 can be pressed into the inner wall of the tail end of the syringe 1 through a press-fitting process, and the rod of the adjustment knob 32 is inserted into the mounting sleeve 31 to form a threaded connection therewith, and the head of the adjustment knob 32 extends out of the mounting sleeve 31, which is convenient for medical staff to perform the screwing operation; accordingly, the injection push rod 2 passes through the adjustment knob 32 and extends into the syringe 1.

[0053] Of course, the mounting sleeve 31 can also be installed externally. In this case, the mounting sleeve 31 is specifically installed on the rear end face of the injection barrel 1, and the adjusting knob 32 is also installed externally.

[0054] like Figure 7 As shown, Figure 7 It is a schematic diagram of the specific structure of the mounting seat 33.

[0055] Furthermore, in order to ensure that the mounting sleeve 31 can be stably mounted in the inner wall of the rear end of the syringe 1, a mounting seat 33 is added in this embodiment. Specifically, the mounting seat 33 is arranged as a whole at the rear end of the syringe 1, and at least two clamping arms 331 are arranged on both sides of the bottom surface of the mounting seat 33, and the two clamping arms 331 are respectively used to clamp and fix the two fins 11 protruding at the rear end of the syringe 1, so as to fix the mounting seat 33 as a whole at the rear end of the syringe 1. At the same time, a mounting through hole 332 is opened on the mounting seat 33, and the mounting through hole 332 exposes the barrel mouth of the syringe 1, and the mounting sleeve 31 is inserted into the syringe 1 through the mounting through hole 332, and the stable installation in the syringe 1 is achieved by connecting with the mounting through hole 332.

[0056] In order to facilitate the stable connection between the mounting sleeve 31 and the mounting through hole 332, in this embodiment, a plurality of snap-fit ​​grooves 333 are provided on the inner wall of the mounting through hole 332, and a plurality of snap-fit ​​protrusions 311 are provided on the outer wall of the mounting sleeve 31. Specifically, 4 to 8 snap-fit ​​grooves 333 can be provided at the same time, and they are evenly or unevenly distributed along the circumferential direction of the mounting through hole 332. Correspondingly, 4 to 8 snap-fit ​​protrusions 311 can be provided at the same time, and they are evenly or unevenly distributed along the circumferential direction of the end of the mounting sleeve 31. Each snap-fit ​​groove 333 can form a snap-fit ​​fit with each corresponding snap-fit ​​protrusion 311, so that the mounting sleeve 31 and the mounting through hole 332 are snap-fitted.

[0057] Of course, a threaded connection or a fixed connection may be formed between the mounting sleeve 31 and the mounting through hole 332 .

[0058] In addition, in order to enable the medical staff to accurately know the target rotation angle of the adjusting knob 32 when turning the adjusting knob 32, in this embodiment, a reference identification line 334 is provided on the top surface of the mounting seat 33, and a scale 321 is provided on the circumference of the adjusting knob 32. Specifically, the reference identification line 334 can be specifically engraved on the top surface of the mounting seat 33 on the outer edge of the mounting through hole 332, and extends along a certain radial direction of the mounting through hole 332, so as to serve as a rotation identification line of the adjusting knob 32. The scale 321 is provided on the outer circumferential surface of the head of the adjusting knob 32, and is mainly used to identify the rotation angle of the adjusting knob 32, or directly identify the corresponding dosage value. For example, when the adjusting knob 32 is rotated 360° clockwise, the adjusting knob 32 moves 1 mm axially, and 32 μl of liquid medicine is injected. If 36 scales 321 are evenly arranged circumferentially on the adjusting knob 32, then when the adjusting knob 32 is rotated clockwise from the initial state until the 18th scale 321 is aligned with the reference marking line 334, the adjusting knob 32 moves 0.5 mm axially, and the corresponding dosage value is 16 μl; at this time, when the medical staff continues to press the injection push rod 2 until the limiter 21 abuts against the adjusting knob 32, the actual injection dosage is precisely 16 μl.

[0059] Of course, the corresponding relationship between the rotation angle of the adjusting knob 32 and its axial movement distance, actual injection dose and other parameters is not fixed and can be adjusted according to actual needs.

[0060] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A prefilled syringe for quantitative administration, comprising a syringe barrel (1) prefilled with a preset amount of liquid medicine, characterized in that: The injection device further comprises an injection push rod (2) which is axially movably inserted into the injection barrel (1), and a dose adjustment mechanism (3) which is axially movably arranged on the injection barrel (1). A limit piece (21) is arranged on the injection push rod (2). The injection push rod (2) is used to push the liquid medicine in the injection barrel (1) to flow out. The dose adjustment mechanism (3) is used to form an abutment with the limit piece (21) to limit the pushing stroke of the injection push rod (2).

2. The prefilled syringe for quantitative administration according to claim 1, characterized in that: The injection push rod (2) comprises a rod body (22), a piston (23) arranged at the front end of the rod body (22), and a pressing plate (24) arranged at the rear end of the rod body (22); the piston (23) is filled in the injection cylinder (1); and the limiting member (21) is arranged on the rod body (22).

3. The prefilled syringe for quantitative administration according to claim 2, characterized in that: The piston (23) is detachably connected to the front end of the rod body (22).

4. The prefilled syringe for quantitative administration according to claim 2, characterized in that: The limiting member (21) is a limiting ring protruding from the circumference of the rod body (22).

5. The prefilled syringe for quantitative administration according to any one of claims 1 to 4, characterized in that: The dose adjustment mechanism (3) comprises a mounting sleeve (31) fixed on the injection barrel (1), and an adjustment knob (32) axially movably arranged in the mounting sleeve (31); the adjustment knob (32) is located on the inner side of the stopper (21) so as to abut against the stopper (21) through its outer end surface.

6. The prefilled syringe for quantitative administration according to claim 5, characterized in that: The inner wall surface of the installation sleeve (31) and the outer wall surface of the adjusting knob (32) form a threaded transmission connection.

7. The prefilled syringe for quantitative administration according to claim 6, characterized in that: The mounting sleeve (31) is mounted inside the injection barrel (1), and the adjusting knob (32) is hollow inside and sleeved on the injection push rod (2).

8. The prefilled syringe for quantitative administration according to claim 5, characterized in that: The dose adjustment mechanism (3) further comprises a mounting seat (33), the bottom surface of which is provided with a clamping arm (331) for clamping and fixing the wing (11) at the rear end of the injection barrel (1), and a mounting through hole (332) for mounting the mounting sleeve (31) is provided on the mounting seat (33).

9. The prefilled syringe for quantitative administration according to claim 8, characterized in that: A plurality of clamping grooves (333) are provided on the inner wall of the mounting through hole (332), and a plurality of clamping protrusions (311) are provided on the outer wall of the mounting sleeve (31), and each of the clamping grooves (333) is used to form a clamping connection with a corresponding clamping protrusion (311).

10. The prefilled syringe for quantitative administration according to claim 8, characterized in that: The top surface of the mounting seat (33) is provided with a reference identification line (334), and the circumference of the adjusting knob (32) is provided with a scale (321) for identifying the rotation angle.

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