CN215504873U - Self-destruction small-dose syringe capable of quantitatively drawing liquid - Google Patents

Abstract

The patent relates to the technical field of injectors, and particularly discloses a self-destructive low-dose injector capable of quantitatively drawing liquid, which comprises a cylinder body, a locking part and a core rod assembly; the cylinder body is at least divided into a push rod part and a liquid containing part; the core rod assembly comprises a user push rod, a first extension body part, a second extension body part and a plug body which are sequentially connected, and further comprises a groove, a plurality of first teeth are arranged in the groove, the core rod assembly can be inserted into the barrel, the first extension body part can completely enter the push rod part, and the second extension body part and the plug body can enter the liquid containing part; a locking member positionable within the recess, the locking member including a first wall and a second wall; also included is a first leg and a second leg, wherein a pull-out on at least one of the legs extends beyond an outer edge of the end with a first barb portion for engaging an inner surface of the barrel to prevent the locking member from sliding in the pull-out direction. This patent makes the syringe wholly destroyed through a motion to avoid syringe part by reuse.

Description

Self-destruction small-dose syringe capable of quantitatively drawing liquid

Technical Field

The utility model relates to the technical field of injectors, in particular to a self-destruction type low-dose injector capable of quantitatively drawing liquid.

Background

Syringe reuse has always been a significant potential in medical treatment worldwide, and the intravenous toxicant population who normally shares and reuses syringes is also a high-risk population of aids, and every year, people become infected with aids virus because of the shared and reused syringes. In addition, in many developing countries, patient life-threatening events are frequent and alarming due to viral cross-contamination among people caused by the repeated use of syringes. Not only are these syringes available, but also are small-dose syringes intended for small-dose injections.

A large number of syringes have been designed in the prior art to address this problem. Some require a specific action to destroy the syringe after use, either by using a destructive device or by providing the syringe with a frangible zone to render it unusable by external force. These areas of weakness are often found on pushers used to push fluids, which can be broken off by force, but do not cause any damage to the barrel of the injector, which can be reused after a plunger has been reattached. On the other hand, the small-dose syringe usually adopts the design of reducing the syringe barrel internal diameter, can lengthen the required stroke of liquid pushing during injection like this, and then make the operation degree of difficulty of drawing liquid and injection reduce, can also reduce the loss, but such design not only need use the push rod of small volume and supporting subassembly, the design space who leaves for the self-destruction mechanism simultaneously also becomes narrow and small, for example among some prior art, the self-destruction mechanism of syringe is set up the blind end at the barrel, need the user to utilize being connected of self-destruction mechanism and push rod to come to exert external force to this blind end, and then accomplish the self-destruction, this just needs to have sufficient space to set up a variety of structures of self-destruction mechanism.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a self-destruction type low-dose injector capable of quantitatively drawing liquid, which can not be reused through one action, so as to solve the technical problem that a part of a syringe can be left undamaged after the self-destruction injector is destroyed once in the prior art, and the syringe can still be partially reused.

The self-destruction type small-dose syringe capable of quantitatively drawing liquid comprises a cylinder body, a locking component and a core rod component;

one end of the cylinder body is an open end, the other end of the cylinder body is a closed end, the cylinder body is at least divided into two sections with different diameters, wherein one section adjacent to the open end is a push rod part with a larger diameter, and the other section adjacent to the closed end is a liquid containing part with a smaller diameter;

the core bar assembly comprises a user push rod, a first extension body part, a second extension body part and a plug body which are sequentially connected, and further comprises a groove arranged along the first extension body part, a plurality of first teeth are arranged in the groove, and the first teeth form a plurality of shoulders facing the pushing direction of the user push rod;

the core rod assembly can be inserted into the cylinder, wherein the first extension body part can completely enter the push rod part, and the second extension body part and the plug body can enter the liquid containing part;

the locking member is positionable within the recess, the locking member including a body portion;

the body portion includes a first wall and a second wall connected along a longitudinal axis and extending radially;

further comprising first and second legs extending from the first and second walls, respectively, in a pull-out direction of the user putter, wherein at least one of the legs includes a pull-out end portion facing in the pull-out direction of the user putter and engageable with the shoulder portion, the pull-out end portion having a first barb portion extending radially outwardly from an outer edge thereof;

a tip of the first barb portion inclined to the pull-out direction for engaging with an inner surface of a barrel to prevent the lock member from sliding in the pull-out direction;

the first teeth are distributed between one end of the groove close to the pull-out direction and the axial middle point of the groove.

Further, the outer edges of the first leg and the second leg are provided with the first barb portions.

Further, the two first barb parts are arranged symmetrically left and right around the longitudinal axis.

Further, a second barb extends radially outwardly from an outer edge of at least one of the first and second walls, a tip of the second barb being inclined in the pull-out direction for engaging an inner surface of the barrel to prevent the locking member from sliding in the pull-out direction.

Further, the outer edges of the first wall and the second wall are provided with the second barb parts respectively.

Further, the two second barb parts are arranged symmetrically left and right around the longitudinal axis.

Further, a gap is left between the first leg and the second leg.

Further, the first and second legs flare outwardly from their connection to the first and second walls.

Further, the locking member is a sheet member made of a metal plate material having elasticity, and a protrusion is provided on a surface thereof.

Furthermore, the user push rod and the first extension body part are integrally formed on the core rod assembly, and a connecting part which is easy to break is arranged between the user push rod and the first extension body part.

Embodiments of the present invention may provide a simple, reliable, and easily manufactured disposable syringe that may become non-reusable without any additional action by the user, using a self-destruction/dosing mechanism formed by a locking member and a first tooth that cannot be retracted with the core rod assembly; meanwhile, the maximum distance that the core rod assembly can retract is changed by utilizing the initial position of the locking component during installation or selecting which group of first teeth the locking component is meshed with, so that quantitative liquid drawing of different doses can be realized, excessive liquid drawing for accurately obtaining the doses is not needed, and redundant doses are wasted. The utility model particularly adopts the liquid containing part with smaller diameter, and simultaneously arranges the locking part in the push rod part with larger diameter, so that the self-destruction/quantification mechanism formed by the locking part and the first tooth can be arranged in the same installation space as a common injector and is not influenced by small-dose liquid drawing and injection, and the use of the self-destruction/quantification mechanism can easily achieve the aims of accurate liquid drawing and injection, so that a very long liquid pushing stroke is formed without adopting very small pipe diameter, therefore, the liquid containing part with smaller diameter only needs to properly reduce the pipe diameter to increase the liquid pushing stroke, and the production difficulty and the cost are both reduced.

And some embodiments of the present invention provide a connection that is easily snapped, allowing the mandrel assembly to break when additional force is applied by the user, resulting in further self-destruction.

Drawings

Fig. 1 is an exploded view of a self-destructive low-dose syringe capable of drawing a constant amount of liquid according to an embodiment of the present invention.

Fig. 2a is a cross-sectional view of the cartridge of fig. 1.

FIG. 2b is a front view of the core rod assembly of FIG. 1.

FIG. 3 is a front view of a core rod assembly in another embodiment of the present invention.

Fig. 4a is a front view of the locking member of fig. 1.

Fig. 4b is a top view of the locking member of fig. 1.

Fig. 5a is a structural diagram of a self-destructive low-dose syringe capable of drawing a constant amount of liquid according to an embodiment of the present invention before use.

Fig. 5b is a structural diagram of the self-destructive low-dose syringe capable of quantitatively drawing liquid according to an embodiment of the present invention after drawing liquid.

Fig. 5c is a structural diagram of the self-destructive low-dose syringe capable of quantitatively drawing liquid according to an embodiment of the present invention after use.

Reference numerals in the drawings of the specification include: the plunger assembly 1, the barrel 2, the liquid containing part 22, the pushing rod part 23, the locking component 3, the protective sleeve 4, the needle seat 21, the puncture needle tube 211, the plug body 5, the user pushing rod 11, the first extending body part 12, the second extending body part 121, the first middle disc 122, the second middle disc 123, the third middle disc 124, the plunger head 13, the press handle 14, the groove 15, the first tooth 16, the shoulder 161, the notch 17, the first wall 31, the second wall 32, the first leg 33, the second leg 34, the pull-out end part 331, the first barb part 332, the second barb part 311 and the protrusion 341.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The self-destructing low dose syringe capable of drawing a metered amount of liquid according to the present invention is basically as shown in fig. 1, and comprises a protective sheath 4, a barrel 2, a locking member 3 and a plunger assembly 1.

The barrel 2 in this embodiment is similar to the barrel of most syringes and has an open end at one end and a closed end at the other end, with a bead extending outwardly from the mouth of the open end to facilitate handling and holding of the syringe by a user. As shown in fig. 2a, the barrel 2 is different from the barrel of the prior art syringe in that the barrel 2 is divided into two sections with different diameters, wherein one section adjacent to the open end is a push rod section 23 with a larger diameter, and the other section adjacent to the closed end is a liquid containing section 22 with a smaller diameter, wherein the liquid containing section 22 is used for containing the liquid medicine. Still integrated into one piece has needle file 21 on the terminal surface of the blind end on barrel 2, and is the same as general syringe needle, be provided with the puncture needle pipe 211 with barrel 2 intercommunication on the needle file 21 along the axis of barrel 2, and this kind of integrated into one piece's needle file 21 and puncture needle pipe 211 wherein are comparatively common in prior art, do not do this and give unnecessary details here. In alternative embodiments, a hub 21 and piercing needle 211 that are separable from barrel 2, as is common in the art, may also be used.

The mandrel assembly 1 includes a plug body 5, a user push rod 11, a first elongated body portion 12, a second elongated body portion, and a recess 15 disposed along the first elongated body portion 12; the second elongate body portion 12112 has a core 13 formed at the end thereof, and the plug body 5 is adapted to fit over the core 13.

As shown in fig. 2b, the first elongated body portion 12 includes a pair of intermediate discs formed at both ends of the first elongated body portion 12, wherein the first intermediate disc 122 is adjacent to the user's push rod 11 and the second intermediate disc 123 is adjacent to the second elongated body portion 121. The portion between the two intermediate discs extends outwardly with vanes which form the aforementioned recesses 15. The side walls of the blades within the recess 15 are formed with a plurality of first teeth 16, each of the first teeth 16 being a ratchet tooth, each first tooth 16 including a shoulder 161 facing in the advancing direction and a ramp extending obliquely downward from the shoulder 161. In this embodiment, the portion of the user's putter 11 between the pressing hand 14 and the first intermediate plate 122 is formed in the same shape as the first elongated body portion 12, except that the first teeth 16 are absent; the second elongated body portion 121 also takes the same shape as the first elongated body portion 12, but in order to accommodate the liquid container 22 having a smaller diameter, the second elongated body portion 121 also has its own diameter reduced, and a third intermediate disk 124 is formed where the end of the second elongated body portion 12112 is connected to the core rod head 13; in addition, in the present invention, the first teeth 16 are required to be distributed only on the portion between the middle disc 121 and the middle point of the groove 15 in the axial direction in the pulling direction in the groove 15, and as shown in fig. 2b, in this embodiment, the length ratio of the portion in the groove 15 where the first teeth 16 are arranged is smaller than the portion where the first teeth 16 are not arranged. In addition, a push handle 14 is formed at one end of the user push rod 11 pointing to the pulling direction thereof, so that the user can push and pull the core bar assembly 1 by applying force.

Preferably, a connecting portion which is easily broken by pulling may be further provided between the user pushing rod 11 and the first elongated body portion 12, and specifically, as shown in fig. 3, a portion of each blade on one side of the user pushing rod 11, which is close to the first intermediate plate 122, is recessed toward the central axis of the core bar assembly 1 to form a notch 17, so as to reduce the cross-sectional area of the core bar assembly 1, more specifically, the cross-sectional area of the user pushing rod 11 portion in this embodiment.

The locking member 3 can be positioned in the recess 15 and the entire core rod assembly 1 can be inserted into the barrel 2 from the open end, wherein the first elongated body portion 12 can enter the push rod portion 23 entirely, the second elongated body portion 121 and the plug body 5 can enter the liquid containing portion 22, and the recess 15 serves as a passage for longitudinal movement of the locking member 3 relative to the first elongated body portion 12.

As shown in fig. 4, the locking member 3 comprises a body portion comprising, connected along a longitudinal axis and extending radially, a first wall 31 and a second wall 32; a first leg 33 and a second leg 34 extending from the first and second walls 32 in the pulling direction of the user push rod 11, respectively, each leg having a pulling end 331 facing in the pulling direction and engageable with the shoulder 161 of the first tooth 16, the two pulling ends 331 each having a first barb 332 extending radially outward from an outer edge thereof, the two first barbs 332 being arranged symmetrically left and right about the longitudinal axis; the tip of the first barb 332 is inclined to the pull-out direction for engaging with the inner surface of the cylinder 2 to prevent the lock member 3 from sliding in the pull-out direction.

Preferably, in the present embodiment, the outer edges of the first wall 31 and the second wall 32 are also extended with the second barb portions 311 radially outward, and the two second barb portions 311 are also arranged in the tip inclined pull-out direction of the second barb portions 311 symmetrically left and right around the longitudinal axis, so as to further enhance the engagement of the locking member 3 with the inner surface of the cylinder 2, so as to prevent the locking member 3 from sliding in the pull-out direction.

As can be seen from fig. 4a, a gap is left between the first leg 33 and the second leg 34, and the first leg 33 and the second leg 34 flare outwards from their connection with the first wall 31 and the second wall 32.

The locking member 3 may be a sheet member made of a resilient metal plate, and the locking member 3 in this embodiment is preferably made of a thin metal plate (e.g., stainless steel). The size of the locking member 3 is selected according to the barrel 2 and core rod assembly 1 used. The angle between the two halves of the locking part 3 in this embodiment is about 90 degrees, and most preferably may be about 100 degrees. When installed in one of the grooves 15 of the core rod assembly 1, the locking member 3 will exert a corresponding force against both side walls of the groove 15. Therefore, even after the locking member 3 is mounted, a gap remains between the first leg 33 and the second leg 34. This clearance is maintained to act as a cantilever spring so that the force on the barrel 2 is relatively reduced to facilitate use and installation of the locking device within the injection sheath. As can be seen from fig. 4a, a hemispherical protrusion 341 is formed on the surface of the second leg 34, and in this embodiment, the protrusion 341 is formed by stamping, and the protrusion 341 can prevent the locking parts 3 from completely fitting when a plurality of locking parts 3 are stacked at one time, so that a gap is left, and the single locking part 3 can be conveniently taken out from the stacked locking parts 3 for assembly in actual production. In other embodiments, the orientation and specific location of the protrusion 341 is not the same as in the present embodiment, but may serve the same purpose. As can be seen in fig. 4a and b, the first wall 31, the second wall 32, the first leg 33 and the second leg 34 have substantially the same width, and as can be seen in fig. 4b, the overall outer contour (before bending) formed by the walls and legs on the same side is substantially rectangular.

The self-destructing low dose syringe with a metered liquid draw-in according to the present embodiment is assembled by placing the locking element 3 in one of the recesses 15, and engaging the two pull-out ends 331 of the locking element 3 with a pair of first teeth 16 on the two side walls of the recess 15 or directly with the first intermediate plate 122. As shown in FIG. 5a, the core rod assembly 1 with the locking element is inserted into the barrel 2, and during the process of pushing the core rod assembly 1 toward the inner end of the barrel 2, the locking element can slide along with the core rod assembly 1 in the barrel 2 due to the tendency of the tips on the first barb 332 and the second barb 311 on the locking element to pull out in the direction. Until the stopper 5 abuts against the end wall of the liquid container 22 in the cylinder 2, so that it can be used or stored. The needle holder 21 may be sleeved with the protective sheath 4 to protect the puncture needle tube 211, and the protective sheath 4 may be removed before use.

In use, as shown in FIG. 5b, plunger assembly 1 is pulled back from the initial position to the second position to draw fluid along piercing needle 211 into well 22 on barrel 2. During such retraction, the locking member 3 remains unmoved and the mandrel assembly 1 is moved outwardly of the barrel 2 relative to the outer sheath 22 and locking member 3. Although the present embodiment shows the locking part 3 having four barbs, the locking part 3 may function with a plurality of barbs or with only one barb, and the number and position of the barbs are selected to improve performance. The pulling out of the first and second legs of the locking member 3 towards the end 331 during retraction of the core assembly 1, beyond the respective first teeth 16 in the groove 15 until the second intermediate disc 123 abuts the end of the locking member 3, the retraction of the core assembly 1 is limited by the locking member 3 since the locking member 3 cannot be retracted, which could damage the barrel 2 if additional axial force is continued to be applied to the core assembly 1. Thus, the amount of drug that can be drawn into the barrel 2 is limited by the maximum distance that the plunger assembly 1 can move, i.e., by the initial position of the locking member 3. Because the grooves 15 are uniformly provided with the plurality of first teeth 16, the maximum retraction distance of different core rod assemblies 1 can be limited only by changing the engagement between the pull-out end 331 of the locking component 3 and the first teeth 16 of several groups during assembly, and a designer can realize different quantitative liquid drawing specifications, such as liquid drawing capacities of 0.01ml,0.05ml and 0.5ml, by limiting the diameter of the liquid containing part 22 on the cylinder body 2, the distance between the first teeth 16 and the structural sizes of the core rod assembly 1 and the locking component 3 according to a cylindrical volume formula by using the same specification assembly. Therefore, when a precise and quantitative injection is required, excessive liquid drawing for obtaining a precise dose is not needed, and an excessive dose is wasted. Particularly for small-dose injection aimed at by the utility model, through the design, even if the liquid containing part 22 with larger size is adopted, the small-dose liquid sucking and injection can be realized more simply by utilizing the distance between the smaller first teeth 16, the traditional injector with small pipe diameter and higher production difficulty is not needed, the operation difficulty is reduced, and the technical requirements on users are also reduced. It should be noted that, during production, the pitch of the first teeth 16 may be set to be equally spaced, or not, depending on how many combinations of liquid-drawing capacities the manufacturer wants to achieve on a group of components; further, the syringe may be provided to the end user as a pre-filled syringe, in which case retraction of the core pin assembly 1 is unnecessary or impossible.

Once fluid is drawn into the well 22 of the barrel 2 from a vial or other fluid source, the needle cannula may be removed from the fluid source and used for injection. During injection of a patient, the user or clinician applies an axial force to the plunger rod assembly 1 and locking member 3. At the end of the injection process, the stopper 5 again abuts against the end wall in the reservoir 22. At this point, as shown in FIG. 5c, the locking element 3 preferably remains distally engaged with the first intermediate disk 122, and the pull-out end 331 engages the last set of first teeth 16 in the recess 15, i.e., the distance between the last set of first teeth 16 and the intermediate disk 121 on the side of the plunger tip 13 is preferably the length of the locking element 3, thereby preventing the plunger assembly 1 from being retracted again, and certainly not being advanced further, so that after a proper dose has been administered, the plunger assembly 1 and locking element 3 will not substantially move from their positions, and thus, this embodiment cannot be reused. Meanwhile, as can be seen from the above description, although providing more first teeth 16 in the recess 15 does not affect the use of the present embodiment and the intended effect thereof, if the last one or more sets of first teeth 16 are located at a distance from the intermediate disk 121 on the side of the core rod head 13 that is less than the length of the locking member 3, these first teeth 16 do not play any role because the present embodiment cannot be used until they are moved to be engaged with the locking member 3. Thus, the requirement of the present invention that the first teeth 16 only be allowed to extend over the portion of the recess 15 between the intermediate disc 121 in the pull-out direction and the axial midpoint of the recess 15 also allows the length of the locking member 3 to be no less than half or even less than half of the length of the first elongated body portion 12, thus reducing the complexity and manufacturing costs of the stem assembly 1 and the locking member 3.

In addition, when using the core rod assembly shown in FIG. 3, if someone applies excessive rotational or bending force to the core rod assembly 1, tries to pull out the locking component 3 or wants to reuse the syringe, the existence of the easily breakable connection may cause the core rod assembly 1 to break, thereby forcing the syringe to be unusable again, and achieving the purpose of further self-destruction.

Those skilled in the art will recognize that the features described in the exemplary embodiments of the present invention are not limited to reduced size syringe assemblies relative to the prior art, and may be used in assemblies for syringes of any desired size.

In an exemplary embodiment of the utility model, the locking member 3 is arranged to be inhaled into the barrel 2 in a dose slightly larger than the dose marked on the barrel 2, preferably about 0.01ml larger. In this embodiment, the user or clinician is able to "air purge" with additional volume to remove any air bubbles that may have entered the barrel 2 without reducing the size of the intended effective dose.

In exemplary embodiments of the present invention, the barrel 2 may be constructed of a variety of thermoplastic materials (e.g., polypropylene, polyethylene, and combinations thereof). In an exemplary embodiment of the utility model, accurate dose setting may be facilitated by the use of materials that provide clear visibility, as well as the use of fixed dose and bold single scale markings on one or more surfaces of the device. Similarly, thermoplastic materials such as polypropylene, polyethylene, and polystyrene are preferred for the core rod assembly 1 and the plug body 5 of the one-piece plug head type. If the plug body 5 is manufactured as a separate component or by a secondary molding process or the like, various materials such as natural rubber, synthetic rubber, and thermoplastic elastomer are suitable for the plug body 5. The choice of stopper 5 material will depend on compatibility with the drug being used and the barrel 2 material and thickness, as the stopper 5 must form a seal with the inside surface of the barrel 2 in order to deliver the drug through the syringe. Further, the plug body 5, the core pin assembly 1, and/or the barrel 2 may be constructed of a colored or colored material or have an applied color to indicate one or more characteristics of the device, such as a needle gauge or a desired dosage. For example, the device may include an ISO color coded core rod assembly 1 to facilitate quick identification of the gauge.

As previously mentioned, the locking element 3 is preferably made of a harder material than the barrel 2 so as to lock the barbs and effectively engage the barrel 2, yet still have some resiliency while also being low cost and consistent size manufacturing considerations. In view of this, a metal plate is an ideal material for the locking member 3, and stainless steel is preferred. Although the locking member 3 of the preferred embodiment is made from a single sheet, it is within the scope of the utility model to include locking members 3 made from other forms and/or comprising multiple members. The locking member 3 may also employ a structure other than the structure shown and described in the present embodiment.

The cartridge 2 used according to the utility model may have a wall thickness that varies along its length. The portion intended to contain the medicament may be relatively thin and resilient to ensure a proper seal with the stopper body 5. The remainder of the barrel 2 may be relatively thick and non-resilient, so that the barrel 2 may crack if squeezed by pliers or other means for attempting tampering.

The self-destruction small-dose syringe capable of quantitatively drawing liquid is automatically locked after injection, so that the syringe is prevented from being reused. It can thus be seen that embodiments of the present invention can provide a simple, reliable, easily manufactured disposable syringe capable of drawing a measured amount of liquid which can be rendered non-reusable without any additional action by the user. The embodiment of the utility model particularly adopts the liquid containing part 22 with a smaller diameter, and simultaneously arranges the locking part in the push rod part 23 with a larger diameter, so that the self-destruction/quantification mechanism formed by the locking part and the first teeth can be arranged in the same installation space of a common injector and is not influenced by small-dose liquid drawing and injection, and the use of the self-destruction/quantification mechanism can easily achieve the aims of accurate liquid drawing and injection, so that a very long liquid pushing stroke is formed without adopting a very small pipe diameter, therefore, the liquid containing part 22 with a smaller diameter only needs to reduce the pipe diameter appropriately to increase the liquid pushing stroke, and the production difficulty and the cost are both reduced.

The above embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and all simple modifications, equivalent changes and modifications made to the above embodiments according to the technical spirit of the present invention still fall within the technical scope of the present invention.

Claims (10)

1. The self-destruction type small-dose syringe capable of quantitatively drawing liquid is characterized by comprising a cylinder body, a locking component and a core rod component;

one end of the cylinder body is an open end, the other end of the cylinder body is a closed end, the cylinder body is at least divided into two sections with different diameters, wherein one section adjacent to the open end is a push rod part with a larger diameter, and the other section adjacent to the closed end is a liquid containing part with a smaller diameter;

the core bar assembly comprises a user push rod, a first extension body part, a second extension body part and a plug body which are sequentially connected, and further comprises a groove arranged along the first extension body part, a plurality of first teeth are arranged in the groove, and the first teeth form a plurality of shoulders facing the pushing direction of the user push rod;

the core rod assembly can be inserted into the cylinder, wherein the first extension body part can completely enter the push rod part, and the second extension body part and the plug body can enter the liquid containing part;

the locking member is positionable within the recess, the locking member including a body portion;

the body portion includes a first wall and a second wall connected along a longitudinal axis and extending radially;

further comprising first and second legs extending from the first and second walls, respectively, in a pull-out direction of the user putter, wherein at least one of the legs includes a pull-out end portion facing in the pull-out direction of the user putter and engageable with the shoulder portion, the pull-out end portion having a first barb portion extending radially outwardly from an outer edge thereof;

a tip of the first barb portion inclined to the pull-out direction for engaging with an inner surface of a barrel to prevent the lock member from sliding in the pull-out direction;

the first teeth are distributed between one end of the groove close to the pull-out direction and the axial middle point of the groove.

2. The self-destructing, low dose liquid scoopable syringe according to claim 1, wherein the first barb portion is provided on an outer edge of each of the first and second legs.

3. The self-destructing, low dose syringe capable of dispensing a metered amount of liquid according to claim 2, wherein the two first barb portions are disposed symmetrically left and right about the longitudinal axis.

4. The self-destructing, low dose, liquid-scoopable syringe according to claim 1, wherein a second barb extends radially outwardly from an outer edge of at least one of the first and second walls, a tip of the second barb being inclined in the pull-out direction for engaging an inner surface of a barrel to prevent the locking member from sliding in the pull-out direction.

5. The self-destructing, low dose liquid scoopable syringe according to claim 4, wherein the second barb portion is provided on an outer edge of each of the first and second walls.

6. The self-destructing, low dose liquid scoopable syringe according to claim 5, wherein the two second barb portions are arranged side-to-side symmetrically about the longitudinal axis.

7. The self-destructing, low dose, liquid-scoopable syringe of claim 1, wherein a gap is left between the first leg and the second leg.

8. The self-destructing, low dose quantifiable liquid draw syringe of claim 1, wherein the first and second legs flare outwardly from their junction with the first and second walls.

9. The self-destructing small dose syringe capable of drawing liquid quantitatively according to claim 1, wherein the locking member is a sheet member made of a resilient metal plate material and has a protrusion on a surface thereof.

10. The self-destructing, low dose syringe of claim 1, wherein the user pushrod is integrally formed with the first elongate body portion on the plunger assembly, and a connection portion is provided between the user pushrod and the first elongate body portion, the connection portion being easily broken by pulling.

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