A syringe

Abstract

The present application relates to the technical field of medical devices, in particular to a syringe, comprising a barrel, one end of the barrel forms a liquid outlet, the other end is slidably provided with a piston rod, one end of the piston rod and located in the barrel is provided with a rubber plug; the liquid outlet is connected with a needle; the needle is detachably capped with a first protective cap; one end of the barrel and close to the needle is provided with a mounting ring, the mounting ring is rotatably provided with a second protective cap, a long slot for placing the needle is formed in the sidewall of the second protective cap; one end of the second protective cap away from the mounting ring is provided with a locking mechanism, when the second protective cap covers the needle, the needle enters the long slot, and the locking mechanism fixes the needle. After use, the needle can be covered to avoid accidental puncture and secondary use.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, in particular to a syringe. Background Art

[0002] The syringe is a common medical device. As early as the 15th century, the Italian physicist, Cardinale, proposed the principle of the syringe. It primarily uses a needle to extract or inject gases or liquids.

[0003] Existing syringes include a barrel, within which a piston rod is mounted. One end of the piston rod is formed with a piston handle, while the other end is located within the barrel and connected to a rubber stopper. A liquid outlet is formed at the end of the barrel away from the piston rod, to which a needle is connected. Existing syringes are generally designed for single use. Before use, the needle is covered with a protective cap. However, these syringes cannot be reused after use. Furthermore, the protective cap on the needle is easily lost after use, making it easy for the needle to be accidentally punctured and potentially causing cross-infection. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In view of the deficiencies of the prior art, the present invention provides a syringe whose needle can be covered after use to avoid accidental punctures and secondary use.

[0006] (2) Technical solution

[0007] To achieve the above-mentioned purpose, an embodiment of the present application provides a syringe, comprising a barrel, a liquid outlet formed at one end of the barrel, and a piston rod slidably provided at the other end, a rubber stopper provided on the piston rod and at one end located in the barrel; a needle is connected to the liquid outlet; a first protective cap is detachably covered on the needle; a mounting ring is provided on the barrel and at one end close to the needle, a second protective cap is rotatably provided on the mounting ring, and a long groove for placing the needle is provided on the side wall of the second protective cap; a locking mechanism is provided on the end of the second protective cap away from the mounting ring, and when the second protective cap covers the needle, the needle enters the long groove, and the locking mechanism fixes the needle.

[0008] Preferably, the needle head includes a needle plug, a needle stem and a needle tip; and a clamping assembly for clamping and limiting the needle plug is provided on the inner side of the long groove.

[0009] Preferably, the clamping assembly includes a first clamping block and a second clamping block fixed to the inner wall of the long groove, the first clamping block and the second clamping block are respectively located on both sides of the needle bolt, and the first clamping block and the second clamping block are close to each other on one side and are respectively provided with an arc-shaped clamping groove, and the clamping groove limits the needle bolt.

[0010] Preferably, an installation box is formed at one end of the second protective cap away from the long slot, the inner side of the installation box is a cavity, and the locking mechanism is arranged in the installation box; a limiting groove is opened on the installation box and on one side close to the long slot, one end of the needle tip passes through the limiting groove and enters the cavity, and the locking mechanism locks and limits the needle entering the cavity.

[0011] Preferably, the locking mechanism includes a guide post, one end of the guide post being located in the installation box, and the other end being connected to the inner wall away from one end of the limit slot; a limit plate is slidably provided on the guide post, and a first guide hole is opened in the middle of the limit plate, and the guide post passes through the first guide hole; a compression spring is sleeved on the guide post, and the compression spring is located on a side of the limit plate away from the limit slot; a limit cylinder is integrally formed on the side of the limit plate close to the limit slot, and the limit cylinder is located on the outer side of the guide post; a limit assembly for limiting the limit plate is provided on the installation box, and when the limit plate is limited, the compression spring is in a compressed state, and the needle enters the installation box from the limit slot; when the limit plate is released from the limit, the limit plate slides under the action of the compression spring, and the limit cylinder is sleeved on the needle entering the installation box and limits the needle.

[0012] Preferably, the inner diameter of the first guide hole is smaller than the inner diameter of the limiting cylinder, and a baffle is provided at the end of the guide column. The baffle is located in the limiting cylinder, and the diameter of the baffle is larger than the inner diameter of the first guide hole.

[0013] Preferably, the limit assembly includes a first support shaft and a second support shaft fixed in the installation box and parallel to each other, the first support shaft and the second support shaft are perpendicular to the guide column, and the first support shaft and the second support shaft are symmetrical about the guide column; a first limit rod is rotatably provided on the first support shaft, and the middle part of the first limit rod is rotatably connected to the first support shaft; a second limit rod is rotatably provided on the second support shaft; the middle part of the second limit rod is rotatably connected to the second support shaft; a limit block is respectively provided at one end of the first limit rod and the second limit rod near the limit disk; when the first limit rod and the second limit rod rotate, the limit block can be engaged with or disengaged from the limit disk; a second guide hole is opened on the inner wall of the installation box away from the limit slot; the guide The column passes through the second guide hole, and an inner guide plate is provided in the installation box, and the inner guide plate is fixedly connected to the guide column, and the guide column extends out of the installation box at one end and is connected to the outer operating plate; an elliptical guide groove is provided on the side of the inner guide plate close to the limit plate; the first limit rod and the second limit rod are embedded in the guide groove at one end away from the limit block and can slide in the guide groove; the width of the guide groove is greater than the width of the first limit rod and the second limit rod, and the short axis length of the guide groove is greater than the outer diameter of the compression spring; when the first limit rod and the second limit rod are located at the two ends of the long axis of the guide groove, the limit block limits the limit plate; when the first limit rod and the second limit rod are located at the two ends of the short axis of the guide groove, the limit block is separated from the limit plate.

[0014] Preferably, when the first limit rod and the second limit rod are located at the two ends of the long axis of the guide groove, the first limit rod and the second limit rod respectively abut against the inner wall of the guide groove; when the first limit rod and the second limit rod are located at the two ends of the short axis of the guide groove, the first limit rod and the second limit rod respectively abut against the outer wall of the guide groove.

[0015] (3) Beneficial effects

[0016] The present invention provides a syringe that, through the provision of a second protective cap and a locking mechanism, can cover the needle after use, preventing the needle tip from accidentally puncturing the staff and preventing cross infection. Furthermore, through the provision of a limit assembly, a limit disc can be released unidirectionally during use. When the limit disc is released, the limit cylinder on the limit disc can form a locking effect on the needle, thereby preventing the syringe from being reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of a syringe according to the present invention;

[0018] Figure 2 A side view of a syringe according to the present invention;

[0019] Figure 3 for Figure 2 A-A sectional view;

[0020] Figure 4 for Figure 2 Cross-sectional view along the B-B direction;

[0021] Figure 5 A cross-sectional view of a locking mechanism protruding from a mounting box in a syringe according to the present invention;

[0022] Figure 6 A schematic diagram of a protruding guide groove in a syringe of the present invention;

[0023] Figure 7 This is a cross-sectional view of a release limit plate of a protruding limit assembly in a syringe of the present invention.

[0024] Markings in the accompanying drawings:

[0025] 100, cylinder; 200, piston rod; 300, needle; 310, needle plug; 320, needle stem; 330, needle tip; 400, first protective cap; 500, mounting ring; 600, second protective cap; 610, long slot; 620, clamping assembly; 621, first clamping block; 622, second clamping block; 623, clamping slot; 630, mounting box; 631, limiting slot; 632, second guide hole; 7 00, locking mechanism; 710, guide column; 720, limit plate; 721, first guide hole; 730, compression spring; 740, limit cylinder; 750, limit assembly; 751, first support shaft; 752, second support shaft; 753, first limit rod; 754, second limit rod; 755, limit block; 756, inner guide plate; 757, outer operating plate; 758, guide groove; 760, baffle. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Example

[0028] The present invention provides a syringe, see Figure 1-Figure 7The device comprises a cylinder 100, with a liquid outlet formed at one end and a piston rod 200 slidably mounted at the other end. A rubber stopper is mounted on one end of the piston rod 200, located within the cylinder 100. A piston handle is mounted at the other end of the piston rod 200. The piston handle allows the piston rod 200 to slide. A needle 300 is connected to the liquid outlet.

[0029] A first protective cap 400 is detachably provided on the needle 300; the first protective cap 400 can protect the needle 300 before use, thereby preventing the needle 300 from being contaminated and preventing the needle 300 from causing accidental puncture to the staff before use.

[0030] A mounting ring 500 is provided on the barrel 100 at one end close to the needle 300 , wherein the mounting ring 500 and the barrel 100 may be connected by bonding.

[0031] A second protective cap 600 is rotatably mounted on the mounting ring 500 . Specifically, a V-shaped connecting plate is rotatably connected between the second protective cap 600 and the mounting ring 500 . The second protective cap 600 can be buckled onto the upper side of the needle 300 through the arrangement of the connecting plate.

[0032] A long slot 610 for placing the needle 300 is formed on the side wall of the second protective cap 600; when the injection is completed, the second protective cap 600 is rotated so that the needle 300 is placed in the long slot 610, and the needle 300 is protected by the second protective cap 600.

[0033] A locking mechanism 700 is provided on the end of the second protective cap 600 away from the mounting ring 500. When the second protective cap 600 covers the needle 300, that is, when the needle 300 enters the elongated slot 610, the locking mechanism 700 secures the needle 300 in place, preventing the needle 300 from dislodging from the elongated slot 610. This locking mechanism 700 ensures that the needle 300 remains within the elongated slot 610 during use, preventing secondary punctures by the needle 300 and thus preventing cross-infection caused by puncture wounds. It also prevents the syringe from being used twice.

[0034] The needle 300 includes a pintle 310, a stem 320, and a needle tip 330. A latch assembly 620 is located inside the slot 610 to secure the pintle 310. When the needle 300 enters the slot 610, the latch assembly 620 secures the pintle 310. The slot 610 secures the needle 300.

[0035] Specifically, the clamping assembly 620 includes a first clamping block 621 and a second clamping block 622 fixed to the inner wall of the elongated slot 610. The first clamping block 621 and the second clamping block 622 are respectively located on either side of the pintle 310. The sides of the first clamping block 621 and the second clamping block 622 adjacent to each other are each provided with an arc-shaped clamping slot 623, which restrains the pintle 310. After use, the second protective cap 600 is rotated toward the needle head 300, and an external force is applied to force the pintle 310 into the space between the two clamping slots 623.

[0036] An installation box 630 is formed at the end of the second protective cap 600 away from the elongated slot 610. The interior of the installation box 630 is a hollow cavity, and a locking mechanism 700 is disposed within the installation box 630. A limiting slot 631 is provided on the side of the installation box 630 near the elongated slot 610. The needle tip 330 of the needle 300 passes through the limiting slot 631 and enters the hollow cavity. The locking mechanism 700 locks the needle 300 in place within the cavity. By locking the needle tip 330 within the installation box 630, the installation box 630 is locked inside, preventing it from being disassembled and reused.

[0037] The locking mechanism 700 includes a guide post 710, one end of which is located within the mounting box 630 and the other end of which is connected to the inner wall of the mounting box 630, away from the end of the retaining groove 631. A retaining plate 720 is slidably mounted on the guide post 710. A first guide hole 721 is defined in the center of the retaining plate 720, through which the guide post 710 passes.

[0038] A compression spring 730 is sleeved on the guide column 710 and is located on a side of the limit plate 720 away from the limit groove 631 ; and when the compression spring 730 is in a compressed state, it can apply elastic force to the limit plate 720 to make it slide along the guide column 710 .

[0039] A limiting cylinder 740 is integrally formed on the limiting disk 720 and located on one side near the limiting groove 631, and the limiting cylinder 740 is located on the outside of the guide column 710; a limiting component 750 is provided on the installation box 630 to limit the limiting disk 720. When the limiting disk 720 is limited, the compression spring 730 is in a compressed state, and the needle 300 enters the installation box 630 from the limiting groove 631; when the limiting disk 720 is unlimited, the limiting disk 720 slides under the action of the compression spring 730, and the limiting cylinder 740 is sleeved on the needle 300 entering the installation box 630, and the limiting cylinder 740 limits the needle 300.

[0040] The inner diameter of the first guide hole 721 is smaller than that of the limiting cylinder 740. A baffle 760 is disposed at the end of the guide post 710. The baffle 760 is located within the limiting cylinder 740 and has a diameter greater than the inner diameter of the first guide hole 721. Due to the baffle 760, when the limiting assembly 750 stops limiting the limiting disk 720, the limiting disk 720 slides outward under the action of the compression spring 730. After sliding a certain distance, the baffle 760 stops it, preventing the limiting disk 720 from continuing to slide off the guide post 710. Furthermore, when the limiting disk 720 is limited by the baffle 760, the position of the limiting cylinder 740 above it can effectively limit the needle 300.

[0041] The limiting assembly 750 includes a first support shaft 751 and a second support shaft 752 fixed in the installation box 630 and parallel to each other. The first support shaft 751 and the second support shaft 752 are perpendicular to the guide column 710 and are symmetrical about the guide column 710.

[0042] A first limiting rod 753 is rotatably provided on the first support shaft 751 , and the middle portion of the first limiting rod 753 is rotatably connected to the first support shaft 751 ; a second limiting rod 754 is rotatably provided on the second support shaft 752 ; the middle portion of the second limiting rod 754 is rotatably connected to the second support shaft 752 .

[0043] A limiting block 755 is provided on each end of the first limiting rod 753 and the second limiting rod 754, respectively, near the limiting plate 720. The limiting blocks 755 are located on a side adjacent to each other. When the first limiting rod 753 and the second limiting rod 754 rotate, the limiting blocks 755 can engage or disengage with the limiting plate 720. When engaged with the limiting plate 720, the compression spring 730 is compressed. When disengaged from the limiting plate 720, the compression spring 730 allows the limiting plate 720 to slide along the guide post 710.

[0044] After the limiting disk 720 slides outward, even if the limiting block 755 returns to its original position, the limiting disk 720 cannot be engaged. At this time, the moved limiting cylinder 740 can maintain the position and fixation of the needle 300. In other words, after locking, it can prevent manual operation to remove the needle 300 again, thus preventing the syringe from being used twice. However, if the limiting disk 720 is separated from the limiting block 755 when the needle 300 has not entered the long groove 610, a tool can be used to enter the limiting groove 631 and press the limiting disk 720 to return it to its original position. After returning to its original position, the limiting block 755 can engage the limiting disk 720.

[0045] A second guide hole 632 is defined on the inner wall of the mounting box 630 at one end away from the limiting slot 631. A guide post 710 passes through the second guide hole 632. An inner guide plate 756 is disposed within the mounting box 630 and fixedly connected to the guide post 710. An outer operating plate 757 is connected to the end of the guide post 710 extending outside the mounting box 630. The inner guide plate 756 and the outer operating plate 757 secure the guide post 710 so that it can rotate within the second guide hole 632. When the outer operating plate 757 rotates, the inner guide plate 756 rotates synchronously.

[0046] An elliptical guide groove 758 is provided on one side of the inner guide plate 756 close to the limiting plate 720 ; the first limiting rod 753 and the second limiting rod 754 are embedded in the guide groove 758 at one end away from the limiting block 755 and can slide in the guide groove 758 .

[0047] Specifically, the width of the guide slot 758 is greater than the widths of the first and second limiting rods 753, 754. When the inner guide plate 756 rotates, the first and second limiting rods 753, 754 are able to slide within the guide slot 758. Because the guide slot 758 is elliptical, during the sliding process, the first and second limiting rods 753, 754 rotate a certain angle about the first and second support shafts 751, 752, respectively. During this rotation, the first and second limiting rods 753, 754 are inclined within the guide slot 758. Because the width of the guide slot 758 is greater than the widths of the first and second limiting rods 753, 754, they are able to complete the sliding motion. The other ends of the first and second limiting rods 753, 754 also rotate, moving toward or away from the limiting plate 720, thereby engaging or disengaging the limiting block 755 from the limiting plate 720.

[0048] The short axis length of the guide groove 758 is greater than the outer diameter of the compression spring 730 , that is, the inner side can be abutted by the compression spring 730 .

[0049] When the first limiting rod 753 and the second limiting rod 754 are located at both ends of the major axis of the guide slot 758, the ends of the first limiting rod 753 and the second limiting rod 754 near the guide slot 758 rotate outwards, and at this time, the ends near the limiting plate 720 rotate toward the center, and the limiting block 755 limits the limiting plate 720. When the first limiting rod 753 and the second limiting rod 754 are located at both ends of the minor axis of the guide slot 758, the first limiting rod 753 and the second limiting rod 754 rotate inwards by a certain angle under the limiting action of the guide slot 758, and at this time, the limiting block 755 disengages from the limiting plate 720.

[0050] To further explain, when the first limiting rod 753 and the second limiting rod 754 are located at the ends of the long axis of the guide groove 758, they respectively abut the inner wall of the guide groove 758. When the first limiting rod 753 and the second limiting rod 754 are located at the ends of the short axis of the guide groove 758, they respectively abut the outer wall of the guide groove 758. When the first limiting rod 753 and the second limiting rod 754 contact the inner wall of the guide groove 758 and then contact the outer wall of the guide groove 758, the limiting plate 720 can be restrained and disengaged. During the installation design, if there are dimensional issues, the swing amplitude of the first and second limiting rods 753 and 754 can be controlled by changing the positions of the first support shaft 751 and the second support shaft 752.

[0051] The present invention provides a syringe. Before use, the first protective cap 400 covers the needle 300 to protect the unused syringe needle 300. After use, the second protective cap 600 is rotated so that the second protective cap 600 covers the needle 300. At this time, the needle tip 330 enters the cavity in the installation box 630 through the limiting groove 631. After the first clamping block 621 and the second clamping block 622 clamp the needle plug 310. The outer operating disk 757 is rotated, and the rotation angle is not less than 180 degrees. At this time, the limiting assembly 750 cancels the limiting effect on the limiting disk 720. The limiting disk 720 slides outward under the action of the compression spring 730 until the limiting cylinder 740 is sleeved on the outside of the needle tip 330, forming a limiting effect on the needle tip 330. At this time, the needle tip 330 is sleeved and limited in the installation box 630 by the limiting cylinder 740.

[0052] The present invention provides a syringe that, through the provision of a second protective cap 600 and a locking mechanism 700, can cover the needle 300 after use, preventing the needle tip 330 from accidentally puncturing a worker and preventing cross infection. Furthermore, the syringe can be locked to prevent the syringe from being reused.

[0053] Finally, it should be noted that when it is necessary to release the locking effect of the needle 300, a tool can be passed through the limiting groove 631 to press the limiting disk 720 or the limiting cylinder 740 to release the restriction on the needle tip 330. However, due to the installation box 630 and the limiting groove 631, ordinary operators cannot release the locking effect, thereby preventing the syringe from being reused.

[0054] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "front," and "back" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0055] In the description of the present invention, it should be noted that, unless otherwise clearly specified or limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection through an intermediate medium, or internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. In the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0056] The above-described embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A syringe comprising a barrel (100), wherein one end of the barrel (100) forms a liquid outlet, and a needle (300) is connected to the liquid outlet; characterized in that: The needle (300) is provided with a detachable cover having a first protective cap (400); a mounting ring (500) is provided on the barrel (100) at one end close to the needle (300); a second protective cap (600) is rotatably provided on the mounting ring (500); a long groove (610) for placing the needle (300) is provided on the side wall of the second protective cap (600); A locking mechanism (700) is provided at one end of the second protective cap (600) away from the mounting ring (500); when the second protective cap (600) covers the needle head (300), the needle head (300) enters the long groove (610), and the locking mechanism (700) fixes the needle head (300); An installation box (630) is formed at one end of the second protective cap (600) away from the long slot (610), the inner side of the installation box (630) is a cavity, and the locking mechanism (700) is arranged in the installation box (630); A limiting groove (631) is provided on the installation box (630) and on one side close to the long groove (610); one end of the needle tip (330) of the needle (300) passes through the limiting groove (631) and enters the cavity; the locking mechanism (700) locks and limits the needle (300) entering the cavity; The locking mechanism (700) comprises a guide post (710), one end of the guide post (710) is located in the installation box (630), and the other end is connected to the inner wall away from the end of the limiting groove (631); A limiting plate (720) is slidably provided on the guide column (710), a first guide hole (721) is provided in the middle of the limiting plate (720), and the guide column (710) passes through the first guide hole (721); A compression spring (730) is sleeved on the guide column (710), and the compression spring (730) is located on a side of the limiting plate (720) away from the limiting groove (631); A limiting cylinder (740) is integrally formed on a side surface of the limiting plate (720) close to the limiting groove (631), and the limiting cylinder (740) is located outside the guide column (710); A limiting assembly (750) for limiting the limiting disk (720) is provided on the installation box (630); when the limiting disk (720) is limited, the compression spring (730) is in a compressed state, and the needle (300) enters the installation box (630) through the limiting groove (631); The limiting assembly (750) includes a first supporting shaft (751) and a second supporting shaft (752) fixed in the installation box (630) and parallel to each other, the first supporting shaft (751) and the second supporting shaft (752) being perpendicular to the guide column (710), and the first supporting shaft (751) and the second supporting shaft (752) being symmetrical about the guide column (710); A first limiting rod (753) is rotatably provided on the first supporting shaft (751), and a middle portion of the first limiting rod (753) is rotatably connected to the first supporting shaft (751); A second limiting rod (754) is rotatably provided on the second support shaft (752); a middle portion of the second limiting rod (754) is rotatably connected to the second support shaft (752); A limiting block (755) is provided at one end of each of the first limiting rod (753) and the second limiting rod (754) close to the limiting plate (720); when the first limiting rod (753) and the second limiting rod (754) rotate, the limiting block (755) can be engaged with or disengaged from the limiting plate (720); A second guide hole (632) is provided on the inner wall of the installation box (630) at one end away from the limiting groove (631); the guide post (710) passes through the second guide hole (632). An inner guide plate (756) is provided in the installation box (630), and the inner guide plate (756) is fixedly connected to the guide column (710). One end of the guide column (710) extending outside the installation box (630) is connected to an outer operating plate (757); An elliptical guide groove (758) is provided on a side of the inner guide plate (756) close to the limiting plate (720); the ends of the first limiting rod (753) and the second limiting rod (754) away from the limiting block (755) are embedded in the guide groove (758) and can slide in the guide groove (758); The width of the guide groove (758) is greater than the width of the first limiting rod (753) and the second limiting rod (754), and the short axis length of the guide groove (758) is greater than the outer diameter of the compression spring (730); When the first limiting rod (753) and the second limiting rod (754) are located at the two ends of the long axis of the guide groove (758), the first limiting rod (753) and the second limiting rod (754) respectively abut against the inner wall of the guide groove (758), and the limiting block (755) limits the limiting plate (720); when the first limiting rod (753) and the second limiting rod (754) are located at the two ends of the short axis of the guide groove (758), the first limiting rod (753) and the second limiting rod (754) respectively abut against the outer wall of the guide groove (758), and the limiting block (755) is separated from the limiting plate (720).

2. A syringe according to claim 1, characterized in that: The needle head (300) comprises a needle plug (310), a needle stem (320) and a needle tip (330); a clamping assembly (620) for clamping and limiting the needle plug (310) is provided inside the long groove (610).

3. A syringe according to claim 2, characterized in that: The clamping assembly (620) includes a first clamping block (621) and a second clamping block (622) fixed to the inner wall of the long slot (610), the first clamping block (621) and the second clamping block (622) are respectively located on both sides of the pintle (310), and an arc-shaped clamping groove (623) is respectively provided on the side where the first clamping block (621) and the second clamping block (622) are close to each other, and the clamping groove (623) limits the pintle (310).

4. The syringe according to claim 1, characterized in that: The inner diameter of the first guide hole (721) is smaller than the inner diameter of the limiting cylinder (740), and a baffle (760) is provided at the end of the guide column (710). The baffle (760) is located in the limiting cylinder (740), and the diameter of the baffle (760) is larger than the inner diameter of the first guide hole (721).

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