CN219049866U - Safety syringe - Google Patents

Abstract

The utility model relates to the technical field of medical instruments, and particularly discloses a safety syringe which comprises a needle cylinder, a needle seat, an injection needle, a ring plug, a push rod, a retraction rod and a compression spring, wherein at least two guide grooves which extend along the axial direction and penetrate through a retraction cavity are uniformly distributed on the outer wall of the push rod along the circumferential direction, stop convex parts which protrude out of the groove wall of the guide groove are arranged at positions, close to the far end, of the guide grooves, guide blocks which are in one-to-one fit with the guide grooves are arranged at the near end of the retraction rod, the guide blocks extend out of the retraction cavity along the guide grooves and protrude out of the outer wall of the push rod, and the compression spring is sleeved on the push rod and positioned between the step surface and the guide blocks. In the structure, based on the structures of the guide block and the stop convex part, the required breakthrough force is larger in the potential energy release process of the compression spring, the possibility of false triggering is almost low, and the reliability is better.

Description

Safety syringe

Technical Field

The utility model relates to the technical field of medical instruments, in particular to a safety syringe.

Background

The injector is a medical instrument with very wide application, and after injection is finished, if an injection needle is in an exposed state, accidental injury is easily caused to a non-patient, and the risk of infection is very high. For this reason, there is an increasing demand for safety syringes that automatically conceal the needle after injection is completed. Wherein, an automatic retraction type safety syringe can automatically retract the injection needle to the inside of the syringe after injection is completed, so as to prevent the exposure of the injection needle.

For example, a self-destroying safety syringe disclosed in chinese patent publication No. CN101284154B is an automatic retracting safety syringe. The self-destruction type safety injector disclosed by the patent is characterized in that after injection is completed, the front end of the retraction rod is connected with the tail end of the needle seat, after the elastic rubber ring breaks through the blocking of the limiting ring, the potential energy of the retraction spring is released, and the assembly formed by the retraction rod, the needle seat and the puncture needle tube is retracted into the barrel body of the push barrel based on the potential energy release of the retraction spring, so that the effect of protecting the injection needle is achieved.

However, the structure disclosed in the above patent still has corresponding defects, specifically including the following technical defects:

(1) The retraction spring is sleeved on the retraction rod and is positioned in the barrel body of the push barrel, and in the installation process, the retraction spring is positioned in a visual field blind area, so that the installation is complex and the installation efficiency is low;

(2) In the initial state, the retraction rod is kept in a corresponding state based on the blocking of the limit ring to the elastic rubber ring, in the process, the potential energy of the retraction spring drives the elastic rubber ring to have a trend of breaking through the limit ring, and the elastic ring is usually a rubber ring, so that the reliability is poor, and the risk of releasing in advance is provided.

Disclosure of Invention

The utility model aims to solve the technical problems that the installation position of a retraction spring is unreasonable and the reliability of an elastic rubber ring serving as a limiting structure is poor in the prior art.

In order to solve the technical problems, the technical scheme provided by the utility model is as follows: a safety syringe comprising at least:

a needle cylinder provided with an inner cavity extending from a proximal end to a distal end, wherein the distal end of the inner cavity is provided with a needle seat mounting part;

the needle stand, the distal end of the said needle stand has injection needles, the proximal end of the said needle stand has the first joint part, the said needle stand enters and installs in the said needle stand mounting part from the proximal end of the said inner chamber;

the proximal end of the needle seat is provided with an annular boss, the annular boss is in interference fit with the inner wall of the inner cavity, an annular cavity for accommodating the annular boss is formed between the annular boss and the distal end of the inner cavity, and the annular plug is in clearance fit with the needle seat and the inner wall of the inner cavity in the annular cavity;

the push rod is positioned in the inner cavity, a retraction cavity is arranged in the push rod, a piston mounting part for mounting a piston is arranged at the far end of the push rod, and a step surface protruding out of the outer wall of the push rod is arranged at the near end side of the piston mounting part;

a retraction rod mounted within the retraction cavity, a distal end of the retraction rod provided with a second engagement portion for mating with the first engagement portion; and

a compression spring;

the outer wall of the push rod is uniformly provided with at least two guide grooves which extend along the axial direction and penetrate through the retraction cavity along the circumferential direction, the position, close to the far end, of the guide groove is provided with stop protruding parts protruding out of the wall of the guide groove, the near end of the retraction rod is provided with guide blocks which are in one-to-one fit with the guide grooves, the guide blocks extend out of the retraction cavity along the guide grooves and protrude out of the outer wall of the push rod, the compression spring is sleeved on the push rod and is located between the step surface and the guide blocks, and in an initial state, the guide blocks are located on the far end side of the stop protruding parts.

In a preferred embodiment, a first protrusion for blocking proximal movement of the ring plug is provided on an inner wall of the inner cavity in a circumferential direction at a position corresponding to a proximal end side of the annular boss.

In a preferred embodiment, the two ends of the inner wall of the ring plug are provided with second protrusions protruding from the inner wall and covering the two sides of the annular boss along the circumferential direction.

In a preferred embodiment, the first engagement portion comprises an engagement groove extending distally from the proximal end face of the hub, the inner wall of the engagement groove being provided with a first engagement protrusion.

In a preferred embodiment, the entrance of the engagement groove is provided with a first guide surface.

In a preferred embodiment, the second engagement portion comprises at least two engagement arms arranged at intervals, a deformation gap is arranged between adjacent engagement arms, and a second engagement protrusion which interacts with the first engagement protrusion is arranged on the outer side of the engagement arms.

In a preferred embodiment, the distal outer side of the engagement arm is provided with a second guiding surface.

In a preferred embodiment, a seal ring is disposed between the distal end of the retraction rod and the retraction cavity.

In a preferred embodiment, the distal side of the guide block is provided with an inwardly sloping ramp.

In a preferred embodiment, the proximal end of the retraction rod is provided with a plurality of cantilevers, the guide block is arranged at the free end of the cantilevers, and the proximal side of the guide block is provided with a guide inclined plane.

In a preferred embodiment, the needle stand comprises a first seat body connected with the needle cylinder and a second seat body detachably connected with the base, and the injection needle is fixedly connected to the second seat body.

In a preferred embodiment, a circumferential limiting structure is arranged between the first seat body and the mounting part of the needle seat.

Compared with the prior art, the safety syringe provided by the utility model has at least the following technical advantages:

(1) The push rod sets up the guide way to set up the backstop convex part at the cell wall of guide way, retract the pole and set up the guide block that stretches out from the guide way, under the initial state, restrict the guide block in the distal end side through backstop convex part, compression spring sets up between piston installation department and guide block, compression spring's potential energy release's prerequisite is, the guide block breaks through the restriction of backstop convex part, in breaking through the in-process, need backstop convex part, the guide way and push rod wall overall deformation, its breakthrough force of needs is great, the possibility of false triggering hardly, the reliability far exceeds prior art.

(2) The compression spring is sleeved on the outer side of the push rod and is located between the piston installation part and the guide block, the installation process is visual, the installation is more convenient, the installation efficiency is higher, and the position setting is more reasonable.

(3) The arrangement of the guide groove and the guide block plays a guiding role in the retraction process of the retraction rod, the resistance encountered in the retraction process of the retraction rod is smaller, the potential energy utilization efficiency of the compression spring is higher, and the retraction speed is faster.

Drawings

FIG. 1 is a schematic view of a safety syringe according to a first embodiment;

FIG. 2 is a schematic view showing an explosive state structure of a safety syringe according to the first embodiment;

FIG. 3 is a schematic view showing the structure of a cylinder of the safety syringe according to the first embodiment;

FIG. 4 is a schematic view showing the structure of the push rod, the retracting rod and the compression spring in the assembled state in the safety syringe according to the first embodiment;

FIG. 5 is a schematic cross-sectional structural view of the structure of FIG. 4;

FIG. 6 is a schematic view showing the structure of a plunger in the safety syringe according to the first embodiment;

FIG. 7 is a schematic perspective view of a retracting lever in the safety syringe of the first embodiment;

FIG. 8 is a schematic elevational view of the retraction lever of FIG. 7;

fig. 9 is a schematic view of a needle holder and an injection needle according to a first structural form of the safety syringe according to the first embodiment;

fig. 10 is a schematic view of the needle hub of fig. 9 in partial cross-section;

fig. 11 is a schematic view of a second structural form of a needle holder and an injection needle in the safety syringe according to the first embodiment;

FIG. 12 is a schematic view showing a partially sectional construction of a safety syringe according to the first embodiment in an initial state;

FIG. 13 is a schematic view showing the structure of a safety syringe according to the first embodiment after adsorbing a medicinal liquid;

fig. 14 is a schematic view of the safety syringe according to the first embodiment after injection of the medical fluid is completed;

fig. 15 is a schematic view of the safety syringe of the first embodiment after the safety syringe of fig. 14 is in the state of continuing to apply pressure to the plunger until the needle hub engages with the retraction lever;

FIG. 16 is a schematic view showing the construction of the safety syringe according to the first embodiment in a state in which the push rod continues to be pressed until the annular plug enters the annular cavity and the guide block breaks through the limit of the stopper protrusion after the state shown in FIG. 15;

FIG. 17 is a schematic view showing the structure of the assembly of the retracting lever, the needle holder and the injection needle retracted into the syringe in the safety syringe according to the first embodiment;

FIG. 18 is a schematic view showing a partial structure of a safety syringe according to the second embodiment in an initial state;

FIG. 19 is an enlarged partial schematic view of portion A of FIG. 18;

fig. 20 is a schematic view showing a partial structure of a cylinder of the safety syringe according to the second embodiment;

FIG. 21 is an enlarged partial schematic view of portion B of FIG. 20;

fig. 22 is a schematic structural view of a ring plug in a safety syringe according to the second embodiment.

Detailed Description

The present utility model will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present utility model more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.

In the description of the present utility model, it should be understood that the directions or positional relationships indicated by the terms "upper", "lower", "front", "rear", "inner", "outer", etc., are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, integrally connected, or detachably connected; may be a communication between the interiors of two elements; may be directly or indirectly through an intermediate medium, and the specific meaning of the terms in the present utility model will be understood by those skilled in the art in specific cases.

In the description of the present utility model, it should be noted that the end of the syringe close to the user is set to be the proximal end and the end close to the patient is set to be the distal end.

Example 1

A safety syringe of this embodiment, as shown in fig. 1-2, includes a barrel 10, a push rod 20, a needle hub 30, a retraction rod 40, a needle 50 compression spring 60, and a protective cap 90. The injection needle 50 is fixedly mounted at the distal end of the needle holder 30, and as shown in fig. 3, the distal end of the needle cylinder 10 is provided with a protective cap combining seat 13 for being matched with a protective cap, and in an initial state, the protective cap 90 is sleeved outside the injection needle 50 and is matched and connected with the protective cap combining seat 13.

In this embodiment, as shown in fig. 3, the syringe 10 is provided with a lumen 11 extending from the proximal end to the distal end, and a plunger 20 is positioned within the lumen 11.

In this embodiment, the distal end of the inner cavity 11 is provided with a hub mounting portion 12, and as shown in fig. 12, the hub 30 is limited to the hub mounting portion 12 by a ring plug 70 after entering from the proximal end of the inner cavity. Specifically, as shown in fig. 9, the proximal end of the needle holder is provided with an annular boss 31, and as shown in fig. 12, the annular plug 70 is mounted between the annular boss 31 and the inner wall of the inner cavity 11 in an interference manner. The ring plug has certain elasticity and can axially displace under the action of external force. In particular, in this embodiment, an annular cavity 16 for accommodating the annular plug 70 is formed between the annular boss 31 and the distal end of the inner cavity 11, and the annular plug 70 is in clearance fit with the needle hub 30 and the inner wall of the inner cavity 11 in the annular cavity 16.

In this embodiment, the syringe 10 is provided with a hand-held operating section 15 near the proximal end, which is a conventional structure of an injector. As a particular feature of this embodiment, as shown in fig. 3, the barrel 30 may be provided with a plurality of through slots 14 extending through the barrel wall of the barrel from the proximal end face toward the hand-held operating portion 15.

In this embodiment, the hub 30 is of a first construction, as shown in Figs. 9-10, and is provided at its proximal end with a first engagement portion. Preferably, in the present embodiment, the first engagement portion includes an engagement groove 33 extending distally from the proximal end face of the hub 30, and the inner wall of the engagement groove 33 is provided with a first engagement protrusion 34.

In this embodiment, as shown in fig. 7-8, the distal end of the retraction rod 40 is provided with a second engagement portion for mating with the first engagement portion. Preferably, in this embodiment, the second engaging portion includes two engaging arms 42 disposed at intervals, a deformation gap 49 is disposed between adjacent engaging arms 42, and a second engaging protrusion 43 that interacts with the first engaging protrusion 34 is disposed on the outer side of the engaging arm 42.

When the distal end of the retraction rod 40 moves toward the proximal end of the needle holder 30 by the external force, the plurality of engagement arms 42 enter the engagement grooves 33, and the engagement arms 42 deform to allow the second engagement protrusions 43 to pass through the positions of the first engagement protrusions 34 based on the arrangement of the deformation gaps 49, at this time, the deformation of the engagement arms 42 is restored, and the retraction rod 40 is engaged with the needle holder 30 as an assembly based on the blocking of the second engagement protrusions 43 by the first engagement protrusions 34.

The retraction lever is typically an injection molded part, and the engagement arm 42 has a certain deformation characteristic.

Preferably, in this embodiment, the first guiding surface 35 is disposed at the entrance of the engaging groove 33, and the second guiding surface 44 is disposed at the outer side of the distal end of the engaging arm 42. Based on the interaction of the first guide surface 35 and the second guide surface 44, the engagement of the retraction rod with the needle hub is more labor-saving and smoother.

It should be noted that the specific structures of the first engaging portion and the second engaging portion in the present embodiment are preferred embodiments of the present embodiment, and any suitable engaging structure in the prior art may be used for the engaging structure of the two.

The push rod 20 of this embodiment is structured as shown in fig. 4 to 6, and is provided with a retraction chamber 22 inside thereof, and is provided at a distal end thereof with a piston mounting portion 25 for mounting the piston 21, and a proximal end side of the piston mounting portion 25 is provided with a stepped surface 26 protruding from an outer wall of the push rod.

As a special feature of this embodiment, two guide grooves 23 extending in the axial direction and penetrating into the retraction cavity 22 are uniformly distributed on the outer wall of the push rod 20 along the circumferential direction, and a stop protrusion 24 protruding from the groove wall of the guide groove is disposed at a position of the guide groove 23 near the distal end. Preferably, in this embodiment, the stop bosses 24 are provided in a pair and are disposed opposite each other.

The retracting lever 40 of this embodiment is structured as shown in fig. 7 to 8, and is provided at its proximal end with two cantilevers 45, and the free end portions of the cantilevers 45 are provided with guide blocks 46 which are one-to-one fitted with the guide grooves 23. As shown in fig. 4-5, wherein the guide block 46 extends from the retraction cavity 21 along the guide slot 23 and protrudes from the outer wall of the push rod 20, the guide block 46 is positioned on the distal side of the stop boss 24 in an initial state, thereby restraining the retraction rod in a distal position of the retraction cavity.

As a special feature of this embodiment, as shown in fig. 4-5, the compression spring 60 is sleeved on the push rod 20 and is located between the step surface 26 and the guide block 46.

Preferably, as shown in fig. 7 to 8, the distal end side of the guide block 46 is provided with an inclined surface 47 inclined inward for the purpose of preventing the compression spring 60 from falling off from the guide block 46.

Preferably, as shown in fig. 7-8, the proximal side of the guide block 46 is provided with a guide ramp 48 which acts to guide the deformation of the cantilever 45 when the guide block 46 is installed from the distal end of the push rod 20 into the retraction cavity.

Preferably, as shown in fig. 4-8, the distal end of the retraction rod 40 is provided with a sealing groove 41 for installing a sealing ring 80, and the sealing ring 80 is installed between the distal end of the retraction rod 40 and the retraction cavity to play a role in sealing and prevent the liquid medicine from entering the retraction cavity. In the present embodiment, the distal end of the seal groove 41 is preferably open, and the seal ring 80 is preferably a rectangular seal ring.

In this embodiment, a second structural form of the needle holder is provided, as shown in fig. 11, the needle holder includes a first holder 301 connected to the needle cylinder and a second holder 302 detachably connected to the base, and the injection needle is fixedly connected to the second holder 302. The purpose of this arrangement is to achieve the effect of changing the gauge of the needle. Generally, the injector body is a finished product, and its seat body is already fixedly installed in the syringe. When in injection, the injection needles with different specifications are arranged on the corresponding second seat body, and a doctor can select the injection needles with the corresponding specifications according to the requirements and is connected to the first seat body.

Preferably, in this embodiment, the first and second holders are connected by a luer connector commonly used in the medical device field, the distal end of the first holder is a male connector, and the proximal end of the second holder is a female connector. It should be noted that this is only a preferred embodiment of the present embodiment, and other detachable connection methods may be used.

In this embodiment, the luer is rotated, so that, in this embodiment, a circumferential limit structure is preferably provided between the first housing and the hub mounting portion 12. Specifically, the seat body is provided with a gear shaping structure 32 adjacent to the annular boss 31, and correspondingly, the needle seat mounting portion 12 is provided with a structure adapted to the gear shaping structure 32. Thus, in the process of rotating and jointing the second seat body and the first seat body, the first seat body is prevented from rotating relative to the needle cylinder.

It should be noted that, when the first embodiment shown in fig. 9 to 10 is adopted for the needle holder 30, the circumferential limit structure may be provided or may not be provided.

Preferably, in this embodiment, as shown in fig. 8, the proximal end of the push rod 20 is provided with a pressing end cap 25, and as shown in fig. 17, in the retracted state after injection, the pressing end cap 25 can enter the inner cavity of the syringe based on the arrangement of the through slot 14, so that the two can be combined together, and repeated insertion and extraction of the push rod can be prevented.

The working principle of the safety syringe of the embodiment is as follows:

(1) In the initial state shown in fig. 1, the cap 90 is pulled out, the internal structure of which is shown in fig. 12, and the distal end of the piston 21 on the push rod 20 is in contact with the proximal end of the needle holder.

(2) The state after the push rod is pulled and the liquid medicine is absorbed is shown in fig. 13.

(3) Pushing the push rod 20, the injection of the drug solution is completed as shown in fig. 14, at which the distal end of the push rod is in contact with the proximal end of the ring plug 70.

(4) Continued pushing of the push rod, as shown in fig. 15, causes the second engagement portion of the retraction rod 40 to engage the first engagement portion of the hub, during which the distal end of the push rod acts on the proximal end face of the ring plug to urge the ring plug into the annular cavity 16.

(5) After the second engagement portion of the retraction rod 40 engages the first engagement portion of the needle hub, as shown in fig. 16, the push rod 20 is continuously pushed, at this time, the position of the retraction rod 40 is relatively fixed, and during the continuous movement of the push rod, the ring plug is pushed into the annular cavity 16, at this time, the interference fit between the needle hub and the inner cavity is released by the ring plug; at the same time, based on the relative movement of the push rod and the retraction rod, the guide block 46 forces the deformation at the stop boss 24, thereby releasing the restriction on the guide block 46 so that the guide block 46 moves to the proximal end side of the stop boss 24.

(6) After the stop boss 24 releases the restriction on the guide block 46, the potential energy of the compression spring 60 is released to drive the assembly of the retraction rod, the needle holder and the injection needle into the syringe to a state as shown in fig. 17, thereby realizing automatic protection of the injection needle.

Example two

A safety syringe according to the present embodiment, as shown in fig. 18 to 22, is different from the first embodiment in that, based on the structure of the first embodiment, a first protrusion 101 for blocking the proximal movement of the annular plug 70 is provided on the inner wall of the inner cavity 11 of the syringe 10 at a position corresponding to the proximal end side of the annular boss 31 in the needle holder 30 in the circumferential direction.

In this embodiment, the first protrusions 101 may be continuous in the circumferential direction or may be a plurality of protrusions distributed at intervals in the circumferential direction. Preferably, the first protrusions 101 are continuous in the circumferential direction.

In this embodiment, the purpose of the first protrusion 101 is that when the needle 50 of the safety syringe enters the medical fluid bottle, the needle holder tends to move proximally, and the first protrusion 101 forms a limit to prevent the assembly of the needle holder and the ring plug from moving proximally.

Further, in this embodiment, in the first embodiment, second protrusions 71 protruding from the inner wall and covering both sides of the annular boss 31 are provided at both ends of the inner wall of the annular plug 70 in the circumferential direction.

In this embodiment, the second protrusions 71 may be continuous in the circumferential direction or may be a plurality of protrusions distributed at intervals in the circumferential direction. Preferably, the second protrusions 71 are continuous in the circumferential direction.

In this embodiment, the second protrusion 71 is provided to prevent the needle holder from being separated from the ring plug because the needle holder tends to move proximally when the needle 50 of the safety syringe is inserted into the vial.

Preferably, in this embodiment, the distal end of the retraction rod 40 is provided with a sealing groove 41 for installing a sealing ring 80, and the sealing ring 80 is installed between the distal end of the retraction rod 40 and the retraction cavity, so as to perform a sealing function and prevent the liquid medicine from entering the retraction cavity. In this embodiment, the difference between the present embodiment and the first embodiment is that the distal end and the proximal end of the seal groove 41 are both closed, and the seal ring 80 is preferably an O-ring.

The working principle of the safety syringe of the embodiment is the same as that of the first embodiment, and will not be described again.

In summary, the foregoing description is only of the preferred embodiments of the utility model, and is not intended to limit the utility model to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the utility model.

Claims (12)

1. A safety syringe comprising at least:

a needle cylinder (10) provided with an inner cavity (11) extending from a proximal end to a distal end, the distal end of the inner cavity being provided with a needle hub mounting portion (12);

a needle seat (30), the distal end of the needle seat is provided with an injection needle (50), the proximal end of the needle seat is provided with a first joint part, and the needle seat enters from the proximal end of the inner cavity and is installed on the needle seat installation part;

the proximal end of the needle seat is provided with an annular boss (31), the annular boss is in interference fit with the inner wall of the inner cavity, an annular cavity (16) for accommodating the annular stopper is formed between the annular boss and the distal end of the inner cavity, and the annular stopper is in clearance fit with the needle seat and the inner wall of the inner cavity in the annular cavity;

the push rod (20) is positioned in the inner cavity, a retraction cavity (22) is arranged in the push rod, a piston mounting part (25) for mounting a piston (21) is arranged at the far end of the push rod, and a step surface (26) protruding out of the outer wall of the push rod is arranged at the proximal end side of the piston mounting part;

a retraction rod (40) mounted within the retraction cavity, a distal end of the retraction rod being provided with a second engagement portion for mating with the first engagement portion; and

a compression spring (60);

the device is characterized in that at least two guide grooves (23) extending along the axial direction and penetrating into the retraction cavity are uniformly distributed on the outer wall of the push rod along the circumferential direction, stop convex parts (24) protruding out of the groove walls of the guide grooves are arranged at positions, close to the distal ends, of the guide grooves, guide blocks (46) which are in one-to-one fit with the guide grooves are arranged at the proximal ends of the retraction rods, the guide blocks extend out of the retraction cavity along the guide grooves and protrude out of the outer wall of the push rod, the compression spring is sleeved on the push rod and located between the step surface and the guide blocks, and the guide blocks are located at the distal ends of the stop convex parts in an initial state.

2. Safety syringe according to claim 1, characterized in that the inner wall of the inner cavity is provided with a first protrusion (101) in the circumferential direction for blocking the proximal movement of the annular plug (70) at a position corresponding to the proximal side of the annular boss (31).

3. Safety syringe according to claim 1 or 2, characterised in that the two ends of the inner wall of the annular plug (70) are provided with second projections (71) protruding from the inner wall and covering the two sides of the annular boss (31) in the circumferential direction.

4. A safety syringe according to claim 1, wherein the first engagement portion comprises an engagement groove (33) extending distally from the proximal end face of the hub, the inner wall of the engagement groove being provided with a first engagement protrusion (34).

5. Safety syringe according to claim 4, characterised in that the entrance of the engagement slot is provided with a first guide surface (35).

6. Safety syringe according to claim 4 or 5, in which the second engagement portion comprises at least two spaced apart engagement arms (42), between adjacent engagement arms a deformation gap (49) is provided, the outer side of the engagement arms being provided with a second engagement protrusion (43) interacting with the first engagement protrusion.

7. A safety syringe according to claim 6, wherein the outer distal end of the engagement arm is provided with a second guide surface (44).

8. A safety syringe according to claim 1, wherein a sealing ring (80) is provided between the distal end of the retraction rod and the retraction cavity.

9. Safety syringe according to claim 1, characterised in that the distal side of the guide block is provided with an inwardly sloping ramp (47).

10. Safety syringe according to claim 1 or 9, characterized in that the proximal end of the retraction lever is provided with a plurality of cantilevers (45), the guide block being provided at the free end of the cantilevers, the proximal side of the guide block being provided with a guide bevel (48).

11. The safety syringe of claim 1 wherein the hub comprises a first housing (301) connected to the barrel and a second housing (302) detachably connected to the base, the needle being fixedly connected to the second housing.

12. The safety syringe of claim 11, wherein a circumferential limit structure is provided between the first housing and the hub mounting portion.

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