CN105797242B

CN105797242B - Syringe with a needle

Info

Publication number: CN105797242B
Application number: CN201610305138.1A
Authority: CN
Inventors: 楚耀强; 周伟; 刘鹏; 叶芊; 林林
Original assignee: Suzhou Mhealthcare Medical Equipment Development Co ltd
Current assignee: Suzhou Mhealthcare Medical Equipment Development Co ltd
Priority date: 2016-05-10
Filing date: 2016-05-10
Publication date: 2021-11-30
Anticipated expiration: 2036-05-10
Also published as: CN105797242A

Abstract

The syringe is used for combining medicament bottle and syringe needle use, its characterized in that includes: the outer protective shell (4), the said outer shell (4) is the hollow body that the front end and rear section form the opening; the inner protective shell is divided into an upper inner protective shell (44) internally provided with a ratchet groove I, a middle inner protective shell (43) internally provided with a rotary groove I and a lower inner protective shell (42) internally provided with a ratchet groove II; the medicine bottle sleeve (2) is connected with the front end of the outer protective shell (4) in an assembling mode, and the medicine bottle sleeve (2) is used for fixing the medicine bottle; the invention has the beneficial effects that: the quantitative adjusting component is used for presetting the injection metering, and the medicine is rapidly injected when being triggered during injection, so that the speed is high, the operation is convenient, and the pain time of a patient is short.

Description

Syringe with a needle

Technical Field

The present invention relates to an injector, and more particularly, to an injector with quantitative injection control and labor-saving operation functions.

Background

For the purpose of quantitative injection of medicine, counting the number of injections, and limited reuse of the syringe, the conventional syringes generally include a metering syringe and a metering syringe. In the known metering injector, a driving mechanism composed of a plurality of driving components is arranged in an injector shell and connected with a push rod, so that a medicament bottle is arranged in the injector shell, a needle is arranged at the front end of the injector shell and connected with the medicament bottle, when in injection, the needle pierces a preset part of a human body, and the push rod is controlled by the driving component which drives the driving mechanism to move in a linkage manner by pressing the rear end of the push rod, so that a piston in the medicament bottle is pushed to move for a preset stroke to output a medicament with a preset dosage through the needle.

If the application number is 201410298104.5, the invention discloses an injector which is used for combining a medicament bottle with a needle head, the injector comprises an outer protective shell, a joint sleeve ring, a medicament bottle casing, an inner sleeve, a bidirectional spiral guide tube group, a screw joint ring, a one-way ratchet, a spiral push rod and an injection push rod group, wherein the joint sleeve ring is arranged at the front end of the outer protective shell, the medicament bottle is combined with the medicament bottle casing to form the medicament bottle, the inner sleeve, the bidirectional spiral guide tube group, the screw joint ring, the one-way ratchet, the spiral push rod, the injection push rod group and the like are assembled in the outer protective shell, so that the injection push rod group can be pulled back directly and quickly and then the injection push rod group is pressed directly to inject, and the large-pitch stroke structure of the bidirectional spiral guide tube group is utilized to match with the small-pitch stroke structure between the screw joint and the spiral push rod, so that the direct pressing force is converted into the rotating force, and the large-stroke rotating thrust is converted into the small-stroke rotating injection thrust force, the purpose of quantitative injection of the medicament is achieved, and the effect of saving labor is achieved by a simple operation mode of circulating opening and closing.

Also disclosed as application No. 201480029399.4 is a drug delivery device adapted to receive a drug cartridge comprising a cartridge holder, an expelling assembly having a piston rod and a coupling. The device further comprises a user-operated actuation mechanism actuatable from a loading state to an intermediate state and from the intermediate state to an operating state, wherein when the actuation mechanism is actuated from the loading state to the intermediate state, the cartridge holder is actuated from a receiving state to a holding state, and when the actuation mechanism is actuated from the intermediate state to the operating state, the coupling is actuated from a free reset state to a locked operating state.

Although the known metering syringe achieves the purpose of quantitatively delivering a medicine, the syringe is limited by the interlocking of the driving parts of the driving mechanism of the syringe during the use and operation, so that the syringe has the problem of labor consuming operation when injecting the medicine, and the injection operation speed is slow, so that the pain of a patient is long.

Disclosure of Invention

The invention overcomes the problems in the prior art, and provides an injector and an injection operation method thereof, which solve the problem of labor waste in operation of the existing metering injector and reduce the pain of the injected person.

The specific technical scheme of the invention is as follows:

the syringe is used for combining medicament bottle and syringe needle use, its characterized in that includes:

the outer protective shell is a hollow body with an opening formed at the front end and the rear section;

the inner protective shell is divided into an upper inner protective shell internally provided with a ratchet groove I, a middle inner protective shell internally provided with a rotary groove I and a lower inner protective shell internally provided with a ratchet groove II;

the medicine bottle sleeve is assembled with the front end of the outer protective shell and used for fixing the medicine bottle therein; the upper part of the quantitative adjusting component is a screw cap, the middle lower part of the quantitative adjusting component is provided with a ratchet spring sheet I which is meshed with the ratchet groove I, the lower part of the quantitative adjusting component is provided with a convex block III, the inner side of the ratchet elastic piece I is connected with an inserting block; a transmission component, the transmission component comprises an adjusting rod and an adjusting nut, the top of the adjusting rod is provided with a spiral lug which is matched with the rotary groove I, the bottom of the adjusting rod is provided with a ratchet elastic sheet III, and the inner side of the adjusting rod is connected with the lug III through a connecting block; the adjusting nut part penetrates in the adjusting rod, a spring is fixed on the adjusting rod, the bottom of the ratchet nut is provided with a female cap, the female cap is provided with a ratchet elastic sheet II, and the inner side of the female cap is provided with a ratchet groove III meshed with the ratchet elastic sheet III; an injection trigger assembly is provided which is adapted to be actuated, the injection triggering component comprises a button rod penetrating the inner side of the screw cap, a pressing sleeve is arranged on the periphery of the button rod, the pressing sleeve can cause the insertion block to move inwards when the button rod is pressed down so that the ratchet elastic piece I is separated from the ratchet groove I meshed with the ratchet elastic piece I;

a screw rod engaged with the piston and axially displacing the piston within the loaded vial housing upon activation of the injection trigger assembly to cause a vial of the vial housing to expel a set dose of the drug;

in another embodiment of the present invention, the upper inner casing, the middle inner casing, and the lower inner casing are sequentially arranged on an inner wall surface of the outer casing from top to bottom, wherein: the middle inner protective shell and the outer protective shell are connected into a whole or the lower inner protective shell and the outer protective shell are connected into a whole or the middle inner protective shell and the lower inner protective shell are simultaneously connected into a whole with the outer protective shell.

Preferably, the upper end and the lower end of the middle inner protective shell are respectively provided with an upper notch for the upper inner protective shell lug to be inserted and assembled and a lower notch for the lower inner protective shell lug to be inserted.

Preferably, the upper inner protective shell, the middle inner protective shell and the lower inner protective shell are all provided with a third bump, and the inner wall of the outer protective shell is provided with a third matching groove for the third bump to be clamped and assembled.

Preferably, the screw rod passes through the adjustment rod and the adjustment nut and is partially installed in the adjustment nut.

Preferably, the button lever comprises a top cap, the lever wall of which is provided with a spring block for blocking the dosing adjustment assembly.

Preferably, an elastic element is further arranged between the quantitative adjusting component and the pressing sleeve.

Preferably, the elastic element is a spring.

Preferably, a pen cap is assembled to the vial casing.

Preferably, the medicine bottle further comprises a return assembly, the return assembly comprises a push-back knob installed at the injection end of the screw rod, the outer wall surface of the push-back knob is provided with a semicircular lug meshed with the medicine bottle casing, the inner side of the push-back knob is provided with an inner ring, a barb extends outwards from the inner ring, and the second spring is installed in a gap between the inner ring and the inner wall surface of the push-back knob. One end of the spring II penetrates through the groove channel to be fixed, and the other end of the spring II extends outwards from the barb.

Preferably, the vial sleeve is at least partially transparent.

Based on the above device, the present invention also provides a method for operating a syringe, characterized by comprising the steps of,

1) preparation before injection: the medicine bottle to be injected is fixed in the medicine bottle casing, and the quantitative adjusting assembly and the return assembly are adjusted to an initial state;

2) setting the injection amount: rotating the quantitative adjusting assembly according to the metering scale mark on the outer wall surface of the rotary quantitative adjusting assembly, so that the quantitative adjusting assembly sequentially actuates the adjusting rod and the adjusting nut to enable the medicine bottle sleeve shell to move upwards to reach a set value, and the spring is in a tense state;

3) and (3) injection: pressing down the button rod to enable the button rod to displace the insertion block inwards through the pressing sleeve to enable the ratchet elastic piece I to be separated from the ratchet groove I meshed with the ratchet elastic piece I; at the moment, the spring in the state of tension loses the limiting force to rebound so that the screw rod advances to the medicine bottle casing in the static state, and the screw rod pushes the piston to make axial displacement, so that the medicine bottle of the medicine bottle casing discharges the medicine with the set metering;

4) adjusting and returning: rotating the vial jacket moves the return assembly relative to the screw rod back to the initial state.

The invention has the beneficial effects that: the quantitative adjusting component is used for presetting the injection metering, and the medicine is rapidly injected when being triggered during injection, so that the speed is high, the operation is convenient, and the pain time of a patient is short.

Drawings

FIG. 1 is a schematic view of the syringe of the present invention;

FIG. 2 is a schematic sectional view of a transmission assembly;

FIG. 3 is a schematic sectional view of an adjusting nut;

FIG. 4 is a bottom view of the adjustment nut;

FIG. 5 is a schematic view of the assembly of the adjusting nut and the lower inner housing;

FIG. 6 is a schematic cross-sectional view of a push-back knob;

FIG. 7 is a schematic view of another orientation and cross-sectional view of the push-back knob;

FIG. 8 is a schematic sectional view of a quantitative adjustment assembly;

FIG. 9 is a bottom view of the dose setting assembly;

FIG. 10 is a schematic view of a button stem configuration;

FIG. 11 is a schematic view of an adjusting lever structure;

FIG. 12 is a schematic view of the connection of the outer protective shell to each inner protective shell;

Detailed Description

Example 1

Referring now more particularly to fig. 1 and 12, a syringe for use with a vial and a needle includes:

the outer protecting shell 4 is a hollow body with an opening formed at the front end and the rear end of the outer protecting shell 4. The medicine bottle sleeve 2 is connected with the front end of the outer protective shell 4 in an assembling mode, and the medicine bottle sleeve 2 is used for fixing the medicine bottle. The vial sleeve 2 is at least partially transparent. Thus, the injection condition and the residual quantity of the medicine bottle can be observed.

The medicine bottle casing 2 is connected with the outer casing 4 in a threaded manner, mainly a threaded port 41 is arranged at the port of the outer casing 4, and the internal thread sleeve 22 at the end part of the medicine bottle casing 2 is connected with the threaded port 41 in an assembling manner, so that the two are connected together. Meanwhile, the pen cap 1 is assembled on the medicine bottle sleeve 2, the pen cap 1 is sleeved on the medicine bottle sleeve 2 when the injector is not used, the main function is to ensure the cleanness and sanitation in the medicine bottle sleeve 2, the injector can also play a role of protection when falling, the protrusion part 25 is pressed at another protrusion part of the medicine bottle sleeve 2 to realize the tight sleeving on the medicine bottle sleeve 2, the mode is universally adopted in the existing ball pen, and the description is omitted.

The inner protective shell is divided into an upper inner protective shell 44 with a ratchet groove I arranged therein, a middle inner protective shell 43 with a rotary groove I arranged therein and a lower inner protective shell 42 with a ratchet groove II arranged therein. The upper inner protective shell 44, the middle inner protective shell 43 and the lower inner protective shell 42 are sequentially arranged on the inner wall surface of the outer protective shell 4 from top to bottom, in this embodiment, the outer protective shells 4 of the upper inner protective shell 44, the middle inner protective shell 43 and the lower inner protective shell 42 are independent from each other.

In addition, the upper inner protecting shell 44, the middle inner protecting shell 43 and the lower inner protecting shell 42 are all provided with a third bump, and the inner wall of the outer protecting shell 4 is provided with a third matching groove for the third bump to be clamped and assembled.

The upper and lower ends of the middle inner sheath 43 are respectively provided with an upper notch 431 for the insertion of the projection of the upper inner sheath 44 and a lower notch 432 for the insertion of the projection of the lower inner sheath 42. Wherein: the third bump on the upper inner protective shell 44 is square, the 42 bump on the lower inner protective shell is isosceles trapezoid, and the two bumps are symmetrically arranged according to the circle center.

In the assembling process, the upper inner protecting shell 44, the middle inner protecting shell 43 and the lower inner protecting shell 42 are sequentially arranged on the inner wall surface of the outer protecting shell 4 from top to bottom, clamped and assembled with the matching groove III for fixation, and simultaneously screwed into the medicine bottle casing 2. The quantitative adjusting assembly 16 is provided with a screw cap 161 at the upper part, a first ratchet spring piece 162 meshed with the first ratchet groove at the middle lower part and a third convex block 164 at the lower part, and an inserting block 166 is connected to the inner side of the first ratchet spring piece 162. The quantitative adjustment unit 16 determines the set injection amount by rotating the quantitative adjustment unit 16 upward by the length of the outer shield 4 to expose the scale due to the scale for setting the injection amount.

The transmission assembly comprises an adjusting rod 10 and an adjusting nut 8, the top of the adjusting rod 10 is provided with a spiral lug 102 which is installed in a matching way with the spiral groove I, the bottom of the adjusting rod is provided with a ratchet elastic sheet III 104, and the inner side of the adjusting rod 10 is connected with the lug III 164 in a phase manner; the adjusting nut 8 is partially penetrated in the adjusting rod 10, the spring 12 is fixed on the adjusting rod 10, the bottom of the adjusting rod is provided with a female cap 82, the female cap 82 is provided with a second ratchet spring piece 83, and the inner side of the female cap is provided with a third ratchet groove 84 meshed with a third ratchet spring piece 104.

The transmission assembly is driven to rotate by the quantitative adjusting assembly 16, specifically, the quantitative adjusting assembly 16 rotates upwards, and is connected with the inner side of the adjusting rod 10 through the third bump 164 in an assembling mode, when the quantitative adjusting assembly 16 rotates, the adjusting rod 10 is driven to rotate, meanwhile, the adjusting rod 10 actuates the adjusting nut 8 through the third ratchet elastic sheet 104, in the process, the first ratchet elastic sheet 162 and the second ratchet elastic sheet 83 move in corresponding ratchet grooves respectively, and move in the ratchet grooves in a unidirectional mode, and when the quantitative adjusting assembly 16 stops rotating, the first ratchet elastic sheet and the second ratchet elastic sheet are restrained by the ratchet grooves and cannot rotate. While the outer jacket 4 and the upper inner jacket 44, the middle inner jacket 43 and the lower inner jacket 42 are stationary during this process, the vial jacket 2 is moved upward relative to the outer jacket 4 by rotation of the dose dial assembly 16, while the spring 12 is tensioned by the rotating band.

An injection trigger assembly, which comprises a button rod 15 penetrating the inner side of a screw cap 161, wherein a pressing sleeve 19 is arranged on the periphery of the button rod 15, and the pressing sleeve 19 can cause an inserting block 166 to displace inwards to enable a ratchet spring piece 162 to be separated from a ratchet groove I engaged with the ratchet spring piece when the button rod 15 is pressed downwards. The button stem 15 includes a top cap 151 with a wall provided with a resilient block 152 that retains the dose setting assembly 16. Between the dosing adjustment assembly 16 and the pressure sleeve 19 there is also provided an elastic element 17, preferably a spring 17.

A screw rod 9, the screw rod 9 engaging the piston 5 and axially displacing said piston 5 within the loaded vial casing 2 upon activation of the injection trigger assembly, thereby causing the vial of the vial casing 2 to be expelled with a set dose of medicament; the screw rod 9 penetrates through the adjusting rod 10 and the adjusting nut 8 and is partially installed in the adjusting nut 8 in a screwing mode.

After the quantitative adjusting assembly 16 is set and adjusted, and injection can be performed, the injection is mainly completed through the following mechanical movement, the button rod 15 is moved downwards through manually pressing the top cap 151, the pressing sleeve 19 is driven by the top cap 151 to be pressed and inserted on the inserting block 166, due to the fact that the inserting block 166 is an inclined surface, when the pressing sleeve 19 goes downwards, the inserting block 166 drives the ratchet elastic piece one 162 to move inwards, and therefore the ratchet elastic piece one 162 is separated from the ratchet groove one meshed with the ratchet elastic piece one, namely the ratchet elastic piece one 162 is not meshed with the ratchet groove one. In this way, the first ratchet spring (162) loses the constraint of the first ratchet groove and returns to the original position under the resilience of the tightening spring 12, and in the action process, the adjusting rod 10 is driven by the resilience to drive the screw rod 9 to axially displace towards the medicine bottle sleeve housing 2, so that the medicine bottle of the medicine bottle sleeve housing 2 discharges the set and metered medicine, and the injection is completed.

In addition, the medicine bottle pushing and returning device further comprises a returning assembly, the returning assembly comprises a pushing and returning knob 3 installed at the injection end of the spiral rod 9, a semicircular lug 36 meshed with the medicine bottle casing 2 is arranged on the outer wall surface of the pushing and returning knob 3, an inner ring 32 is arranged on the inner side of the pushing and returning knob, a barb 33 extends outwards from the inner ring 32, and a second spring 6 is installed in a gap between the inner ring 32 and the inner wall surface of the pushing and returning knob 3. One end of the second spring 6 penetrates through the groove 34 to be fixed, and the other end of the second spring extends out of the barb 33.

After the whole bottle injection is completed, the screw rod 9 needs to be adjusted back to the initial position so as to be convenient for changing the injector to be used next time, specifically, the push-back knob 3 rotates relative to the medicine bottle casing 2 to bring the screw rod 9 back to the original position through rotating the medicine bottle casing 2.

Example 2

In this embodiment, the lower inner casing 42 of the inner casing is integrally connected to the outer casing 4, i.e. both are a single component. The rest of the structure is the same as in example 1.

Example 3

In this embodiment, the middle inner casing 43 of the inner casing is integrally connected to the outer casing 4, i.e. both are a single component. The rest of the structure is the same as in example 1.

Example 4

In this embodiment, the inner casing 43 and the lower inner casing 42 are connected to the outer casing 4 at the same time, i.e. they are a single part. The rest of the structure is the same as in example 1.

Based on the device described in the above 4 embodiments, the present invention also provides a method for operating a syringe, which is characterized by comprising the following steps,

1) preparation before injection: the medicine bottle to be injected is fixed in the medicine bottle casing 2, and the quantitative adjusting assembly 16 and the return assembly are adjusted to the initial state;

2) setting the injection amount: rotating the quantitative adjusting component 16 according to the metering scale mark on the outer wall surface of the rotary quantitative adjusting component 16, so that the quantitative adjusting component 16 sequentially actuates the adjusting rod 10 and the adjusting nut 8 to enable the medicine bottle sleeve housing 2 to move upwards to reach a set value, and at the moment, the spring 12 is in a tight state;

3) and (3) injection: the button rod 15 is pressed down, the insertion block 166 is displaced inwards through the pressing sleeve 19, and the ratchet spring piece I162 is separated from the ratchet groove I meshed with the ratchet spring piece I; at this time, the spring in the state of the tensed spring 12 loses the limiting force to rebound so that the screw rod 9 advances towards the medicine bottle casing 2 in the static state, and the screw rod 9 pushes the piston (5) to make axial displacement, so that the medicine bottle of the medicine bottle casing 2 discharges the medicine with the set metering;

4) adjusting and returning: rotating the vial jacket 2 moves the return assembly relative to the screw 9 back to the initial state. The term "drug" or "agent" as used herein means a pharmaceutical formulation containing at least one pharmaceutically active compound. For example:

1. the pharmaceutically active compound has a molecular weight of up to 1500Da and/or is a peptide, protein, polysaccharide, vaccine, DNA, RNA, enzyme, antibody or fragment thereof, hormone or oligonucleotide, or a mixture of the above pharmaceutically active compounds,

2. the pharmaceutically active compounds are useful for the treatment and/or prophylaxis of diabetes mellitus or complications associated with diabetes mellitus such as diabetic retinopathy, thromboembolic disorders such as deep vein or pulmonary thromboembolism, Acute Coronary Syndrome (ACS), angina pectoris (angina), myocardial infarction, cancer, macular degeneration, inflammation, hay fever, atherosclerosis and/or rheumatoid arthritis,

3. the pharmaceutically active compound comprises at least one peptide for the treatment and/or prevention of diabetes or complications associated with diabetes such as diabetic retinopathy,

4. the pharmaceutically active compound comprises at least one human insulin or a human insulin analogue or derivative, a glucagon-like peptide (GLP-1) or an analogue or derivative thereof, or exedin-3 or exedin-4, or an analogue or derivative of exedin-3 or exedin-4.

5. Hormones are, for example, pituitary hormones or hypothalamic hormones or regulatory active peptides and their antagonists, as listed in rote list, version 2008, chapter 50, such as gonadotropin (gonadoropine) (Follitropin), luteinizing hormone (Lutropin), chorionic gonadotropin (chorionic gonadotropin), gametogorotropin (Menotropin), growth hormone (Somatropin), Desmopressin (Desmopressin), Terlipressin (Terlipressin), Gonadorelin (Gonadorelin), Triptorelin (Triptorelin), Leuprorelin (Leuprorelin), Buserelin (Buserelin), Nafarelin (Nafarelin), Goserelin (Goserelin).

6. Polysaccharides are, for example, glycosaminoglycans, hyaluronic acid, heparin, low molecular weight heparin or ultra-low molecular weight heparin or derivatives thereof, or sulfates, for example, polysulfated forms of the above mentioned polysaccharides, and/or pharmaceutically acceptable salts thereof. An example of a pharmaceutically acceptable salt of a polysulfated low molecular weight heparin is enoxaparin sodium (enoxaparin).

7. Antibodies are globular plasma proteins (-150 kDa), also known as immunoglobulins that share a basic structure. They are glycoproteins because they have sugar chains added to amino acid residues. The basic functional unit of each antibody is an immunoglobulin (Ig) monomer (containing only one Ig unit); the secreted antibody may also be a dimer with two Ig units such as IgA, a tetramer with four Ig units such as teleost IgM, or a pentamer with five Ig units such as mammalian IgM.

And pharmaceutically acceptable solvates such as hydrates.

In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.

Claims

1. The syringe is used for combining medicament bottle and syringe needle use, its characterized in that includes:

the outer protective shell (4), the said outer protective shell (4) is the hollow body that the front end and rear section form the opening;

the inner protective shell is divided into an upper inner protective shell (44) internally provided with a ratchet groove I, a middle inner protective shell (43) internally provided with a rotary groove I and a lower inner protective shell (42) internally provided with a ratchet groove II;

the medicine bottle casing (2), the medicine bottle casing (2) is assembled and connected with the front end of the outer casing (4) and used for fixing the medicine bottle therein; wherein: the medicine bottle casing is connected with the outer casing in a threaded mode, a threaded port is formed in the port of the outer casing, and the internal thread sleeve at the end of the medicine bottle casing is connected with the threaded port in an assembling mode to enable the medicine bottle casing and the outer casing to be connected together;

the quantitative adjusting assembly (16) is provided with a screw cap (161) at the upper part, a first ratchet elastic sheet (162) meshed with the first ratchet groove at the middle lower part and a third convex block (164) at the lower part, and an inserting block (166) is connected to the inner side of the first ratchet elastic sheet (162);

the transmission assembly comprises an adjusting rod (10) and an adjusting nut (8), the top of the adjusting rod (10) is provided with a spiral lug (102) which is installed in a matched mode with the spiral groove I, the bottom of the adjusting rod is provided with a ratchet elastic sheet III (104), and the inner side of the adjusting rod (10) is connected with the lug III (164) in a combined mode; the adjusting nut (8) is partially penetrated in the adjusting rod (10), a spring (12) is fixed on the adjusting rod (10), a female cap (82) is arranged at the bottom of the adjusting rod, a second ratchet elastic sheet (83) is arranged on the female cap (82), and a third ratchet groove (84) meshed with a third ratchet elastic sheet (104) is arranged on the inner side of the female cap;

the injection trigger assembly comprises a button rod (15) penetrating the inner side of a screw cap (161), a pressing sleeve (19) is installed on the periphery of the button rod (15), and the pressing sleeve (19) can cause an insertion block (166) to displace inwards to enable a ratchet spring piece (162) to be separated from a ratchet groove I meshed with the ratchet spring piece when the button rod (15) is pressed downwards;

a screw rod (9), the screw rod (9) engaging the piston (5) and axially displacing said piston (5) within the loaded vial case (2) upon activation of the injection trigger assembly to cause the vial of the vial case (2) to expel a set dose of medicament.

2. The syringe according to claim 1, characterized in that the upper inner sheath (44), the middle inner sheath (43) and the lower inner sheath (42) are arranged on the inner wall surface of the outer sheath (4) from top to bottom in sequence, wherein: the upper inner protective shell (44), the middle inner protective shell (43) and the lower inner protective shell (42) are independent of each other, the middle inner protective shell (43) and the outer protective shell (4) are connected into a whole, or the lower inner protective shell (42) and the outer protective shell (4) are connected into a whole, or the middle inner protective shell (43) and the lower inner protective shell (42) are simultaneously connected with the outer protective shell (4) into a whole.

3. The syringe according to claim 1, wherein the upper end and the lower end of the middle inner sheath (43) are respectively provided with an upper notch (431) for insertion and assembly of the projection of the upper inner sheath (44) and a lower notch (432) for insertion of the projection of the lower inner sheath (42).

4. The syringe as claimed in claim 1, characterized in that the upper inner protective shell (44), the middle inner protective shell (43) and the lower inner protective shell (42) are provided with a third projection, and the inner wall of the outer protective shell (4) is provided with a third matching groove for the third projection to be clamped and assembled.

5. Syringe according to claim 1, characterized in that said screw (9) passes through the adjustment rod (10) and the adjustment nut (8) and is partially mounted screwed inside the adjustment nut (8).

6. The syringe of claim 1, characterized in that the button stem (15) comprises a top cap (151) having a wall provided with a bullet (152) for retaining the dosing assembly (16).

7. Syringe according to claim 1, characterised in that an elastic element (17) is also provided between the metering assembly (16) and the pressure sleeve (19).

8. Syringe according to claim 7, characterised in that said elastic element (17) is a spring.

9. Injector according to claim 1, characterized in that the cartridge housing (2) is fitted with a pen cap (1).

10. The syringe according to any one of claims 1 to 9, further comprising a return assembly including a push-back knob (3) mounted on the injection end of the screw rod (9), wherein the push-back knob (3) has a semicircular protrusion (36) on the outer wall surface thereof for engaging with the medicine bottle case (2), an inner ring (32) on the inner side thereof, a barb (33) extending from the inner ring (32) to the outer side thereof, and a second spring (6) mounted in a gap between the inner ring (32) and the inner wall surface of the push-back knob (3).

11. The syringe according to claim 10, characterized in that the second spring (6) is fixed with one end passing through the channel (34) and the other end extending out of the barb (33).

12. Injector according to any of claims 1 to 9, characterized in that the vial jacket (2) is at least partially transparent.

13. Injector according to claim 10, characterized in that the vial jacket (2) is at least partially transparent.