A sealed injection needle

Abstract

The application discloses a sealed injection needle. The injection needle comprises a negative pressure seat, an inner container needle seat and a plurality of needle tubes. The lower end face of the negative pressure seat is provided with a plurality of limiting guide cylinders, and the lower end face of the inner container needle seat is provided with a plurality of needle seat cylinders which are connected with the limiting guide cylinders one by one. The limiting guide cylinders comprise upper end sealing cavities, middle part sealing cavities and lower end sealing cavities, and the needle seat cylinders comprise upper end cylinders, middle part cylinders and lower end cylinders. The limiting guide cylinders and the needle seat cylinders are connected in a stepped and stepped sealing mode, so that the sealing effect of the injection needle is improved, and the multi-stage sealing connection mode can prevent the transparent beauty liquid from flowing back to the upper end of the inner cavity of the negative pressure seat.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, in particular to a sealed injection needle. BACKGROUND

[0002] With the continuous development of the medical beauty industry, multi-head injection needles have become popular products in the medical beauty industry due to their high safety, small trauma, and good cosmetic effect. After the multi-head injection needle is assembled with the syringe, it is used with an electronic injection instrument. The transparent cosmetic liquid is injected into the subcutaneous dermis layer through the negative pressure principle, so as to improve the skin state of the patient's face and ultimately achieve the effect of beauty.

[0003] At present, most of the multi-head injection needles on the market include a needle seat, a needle tube, a cone seat, a negative pressure seat, and an adjusting seat. The adjusting seat and the negative pressure seat are tightly buckled, the liquid inlet luer connector of the cone seat has external threads, the center hole of the adjusting seat has internal threads, the center hole of the cone seat and the adjusting seat are threadedly connected, the rotating adjusting seat drives the cone seat, the needle seat, and the needle tube to move up and down, and the needle length of the needle tube changes, thereby achieving the purpose of adjusting the needle length. Such a structure is disclosed in patent CN220046829U. Because the inner cavity of the needle seat and the negative pressure seat is in a conical surface fitting mode, when the needle length of the needle tube is the longest, the inner wall surface of the needle seat and the negative pressure seat is in a tightly fitted state. When the needle length of the needle tube is shortened, a gap is generated between the inner wall surface of the needle seat and the negative pressure seat. Therefore, there is a risk that the transparent cosmetic liquid flows back through the gap between the inner wall surface of the needle seat and the negative pressure seat to the upper end of the inner cavity of the negative pressure seat, and then flows out from the hollow hole (injection molding process hole) on the adjusting seat to the outside of the injection needle. SUMMARY

[0004] The present application provides a sealed injection needle, which can solve the technical problem that a gap is generated between the inner wall surface of the needle seat and the negative pressure seat, resulting in a risk that the transparent cosmetic liquid flows back through the gap between the inner wall surface of the needle seat and the negative pressure seat to the upper end of the inner cavity of the negative pressure seat, and then flows out from the hollow hole on the adjusting seat to the outside of the injection needle.

[0005] The embodiment of the present application provides a kind of injection needle with sealing performance, the injection needle includes negative pressure seat, inner container needle seat and several needle tubes;The inner container needle seat is installed in the inner cavity of the negative pressure seat, the lower end face of the negative pressure seat is equipped with several limiting guide cylinders, the lower end face of the inner container needle seat is equipped with several needle seat cylinders, the needle seat cylinder is connected with the limiting guide cylinder one by one, the needle tube is arranged in the needle seat cylinder, the needle tube protrudes from the lower end face of the negative pressure seat through the limiting guide cylinder;The limiting guide cylinder includes upper end sealing cavity, middle part sealing cavity and lower end sealing cavity, the inner diameter of the upper end sealing cavity is greater than the inner diameter of the middle part sealing cavity, the inner diameter of the middle part sealing cavity is greater than the inner diameter of the lower end sealing cavity, the inner diameter of the lower end sealing cavity is equal to the outer diameter of the needle tube, and the lower end sealing cavity is sealingly connected with the needle tube;The needle seat cylinder includes upper end cylinder, middle part cylinder and lower end cylinder, the outer diameter of the upper end cylinder is greater than the outer diameter of the middle part cylinder, the outer diameter of the middle part cylinder is greater than the outer diameter of the lower end cylinder, and the upper end cylinder is located at the upper edge opening position of the upper end sealing cavity, the middle part cylinder is sealingly arranged in the upper end sealing cavity, and the lower end cylinder is sealingly arranged in the middle part sealing cavity.

[0006] Further, the upper end sealing cavity, the middle part sealing cavity and the lower end sealing cavity are smoothly connected, the upper end cylinder, the middle part cylinder and the lower end cylinder are smoothly connected, the transition cavity surface between the upper end sealing cavity and the middle part sealing cavity is matched with the transition curved surface between the middle part cylinder and the lower end cylinder, and the transition curved surface is sealingly matched with the transition cavity surface when the needle seat cylinder extends into the bottom of the limiting guide cylinder.

[0007] Further, the outer side surface of the needle seat cylinder is clearance fitted with the inner side surface of the limiting guide cylinder, and the clearance of the clearance fitting is in the range of 0-0.02mm.

[0008] Further, the outer side surface of the needle seat cylinder is interference fitted with the inner side surface of the limiting guide cylinder, and the interference amount of the interference fitting is in the range of 0-0.15mm.

[0009] Further, the upper edge opening of the upper end sealing cavity is a flexible elastic thin-walled structure, the inner side of the upper edge opening of the upper end sealing cavity is provided with a ring buckle structure, the ring buckle structure is interference fitted with the middle part cylinder, and the interference amount of the interference fitting is in the range of 0-0.15mm.

[0010] Further, the ring buckle structure is a right-angle type ring buckle, the right-angle side of the right-angle type ring buckle is flush with the upper edge opening of the upper end sealing cavity, and the inner diameter of the right-angle type ring buckle gradually increases from the upper edge opening of the upper end sealing cavity to the side towards the middle part sealing cavity;Or,

[0011] The ring buckle structure is a rhombus type ring buckle, the upper end of the rhombus type ring buckle is flush with the upper edge opening of the upper end sealing cavity, the middle part of the rhombus type ring buckle is provided with a turning point, the inner diameter of the rhombus type ring buckle gradually decreases from the upper edge opening of the upper end sealing cavity to the turning point, and the inner diameter of the rhombus type ring buckle gradually increases from the turning point to the side of the middle part sealing cavity; or,

[0012] The ring buckle structure is an arc type ring buckle, the upper end of the arc type ring buckle is flush with the upper edge opening of the upper end sealing cavity, and the inner diameter of the arc type ring buckle gradually decreases and then increases in an arc shape from the upper edge opening of the upper end sealing cavity to the side of the middle part sealing cavity.

[0013] Further, the outer side of the middle part cylinder is provided with a sealing protruding structure, and the sealing protruding structure is located at the position of the middle part cylinder adjacent to the lower end cylinder.

[0014] Further, the sealing protruding structure is a right angle type protrusion, the right angle side of the right angle type protrusion is flush with the lower edge of the middle part cylinder, and the outer diameter of the right angle type protrusion gradually decreases from the lower edge of the middle part cylinder to the side of the upper end cylinder; or,

[0015] The sealing protruding structure is a rhombus type protrusion, the lower end of the rhombus type protrusion is flush with the lower edge of the middle part cylinder, the middle part of the rhombus type protrusion is provided with a protruding point, the outer diameter of the rhombus type protrusion gradually increases from the lower edge of the middle part cylinder to the protruding point, and the outer diameter of the rhombus type protrusion gradually decreases from the protruding point to the side of the upper end cylinder; or,

[0016] The sealing protruding structure is an arc type protrusion, the upper end of the arc type protrusion is flush with the lower edge of the middle part cylinder, and the outer diameter of the arc type protrusion gradually increases and then decreases in an arc shape from the lower edge of the middle part cylinder to the side of the upper end cylinder.

[0017] Further, the injection needle further comprises a cone seat and an adjusting seat, the inside of the cone seat is provided with a hollow liquid guide pipe, the bottom surface of the cone seat is provided with a liquid distribution cavity, the liquid distribution cavity is connected with the needle seat cylinder one by one, and the top of the needle tube is communicated to the liquid distribution cavity; the center of the adjusting seat is provided with a threaded through hole, the outer side of the cone seat is provided with an outer threaded circular table, the outer threaded circular table is threadedly connected with the threaded through hole, a plurality of clamping blocks are arranged on the peripheral wall surface of the adjusting seat in a ring direction, the outer part of the negative pressure seat is provided with a ring eave body, and the adjusting seat is clamped on the ring eave body through the clamping blocks.

[0018] Further, the top of the inner container needle seat is further provided with a plurality of positioning bosses, the positioning bosses are arranged at intervals with the needle seat cylinder, the bottom surface of the cone seat is provided with a plurality of limiting grooves, and the positioning bosses are connected with the limiting grooves one by one.

[0019] The injection needle with sealing performance provided by the embodiment of the application has the following advantages: the injection needle comprises a negative pressure seat, an inner container needle seat and a plurality of needle tubes, the lower end surface of the negative pressure seat is provided with a plurality of limiting guide cylinders, the lower end surface of the inner container needle seat is provided with a plurality of needle seat cylinders, the needle seat cylinders are connected with the limiting guide cylinders one by one, the limiting guide cylinders comprise an upper end sealing cavity, a middle part sealing cavity and a lower end sealing cavity, the needle seat cylinders comprise an upper end cylinder, a middle part cylinder and a lower end cylinder, the limiting guide cylinders and the needle seat cylinders are connected in a stepped manner, the sealing effect of the injection needle is improved, and the multi-stage sealing connection mode avoids backflow of the transparent beauty liquid to the upper end of the inner cavity of the negative pressure seat. BRIEF DESCRIPTION OF DRAWINGS

[0020] The technical scheme and other beneficial effects of the application will be apparent through the following detailed description of the specific embodiments of the application in combination with the drawings.

[0021] Figure 1 The structure schematic diagram of the injection needle with sealing performance provided by the embodiment of the application is shown in the figure;

[0022] Figure 2 The exploded structure schematic diagram of the injection needle with sealing performance provided by the embodiment of the application is shown in the figure;

[0023] Figure 3 The cross-sectional view of the injection needle with sealing performance provided by the embodiment of the application is shown in the figure;

[0024] Figure 4 The assembly structure schematic diagram of the injection needle with sealing performance provided by the embodiment of the application is shown in the figure;

[0025] Figure 5 The structure schematic diagram of the negative pressure seat provided by the embodiment of the application is shown in the figure;

[0026] Figure 6 The structure schematic diagram of the negative pressure seat provided by the embodiment of the application is shown in the figure;

[0027] Figure 7 The structure schematic diagram of the inner container needle seat provided by the embodiment of the application is shown in the figure;

[0028] Figure 8 The cross-sectional view of the inner container needle seat provided by the embodiment of the application is shown in the figure;

[0029] Figure 9 The connection structure schematic diagram of the needle seat cylinder and the limiting guide cylinder provided by the embodiment of the application is shown in the figure;

[0030] Figure 10 The structure schematic diagram of the limiting guide cylinder provided by the embodiment of the application is shown in the figure;

[0031] Figure 11The first structure of the ring buckle structure provided by the limiting guide cylinder of the embodiment of the application is partially enlarged;

[0032] Figure 12 The second structure of the ring buckle structure provided by the limiting guide cylinder of the embodiment of the application is partially enlarged;

[0033] Figure 13 The third structure of the ring buckle structure provided by the limiting guide cylinder of the embodiment of the application is partially enlarged;

[0034] Figure 14 The structure schematic diagram of the needle seat cylinder provided by the embodiment of the application is shown;

[0035] Figure 15 The first structure of the sealing protrusion structure provided by the needle seat cylinder of the embodiment of the application is partially enlarged;

[0036] Figure 16 The second structure of the sealing protrusion structure provided by the needle seat cylinder of the embodiment of the application is partially enlarged;

[0037] Figure 17 The third structure of the sealing protrusion structure provided by the needle seat cylinder of the embodiment of the application is partially enlarged;

[0038] Figure 18 The structure schematic diagram of the conical seat provided by the embodiment of the application is shown;

[0039] Figure 19 The structure schematic diagram of the adjusting seat provided by the embodiment of the application is shown;

[0040] Figure 20 The cooperation structure schematic diagram of the conical seat, the negative pressure seat, the inner container needle seat and the plurality of needle tubes provided by the embodiment of the application is shown.

[0041] The identification in the figure is as follows:

[0042] The negative pressure seat 1, the limiting guide cylinder 11, the upper end sealing cavity 111, the middle part sealing cavity 112, the lower end sealing cavity 113, the ring buckle structure 12, the ring eaves body 13, the inner container needle seat 2, the needle seat cylinder 21, the upper end cylinder 211, the middle part cylinder 212, the lower end cylinder 213, the sealing protrusion structure 22, the positioning boss 23, the guide positioning rib 24, the needle tube 3, the conical seat 4, the empty guide liquid tube 41, the liquid separation cavity 42, the outer thread circular table 43, the limiting groove, the guide groove 44, the adjusting seat 5, the threaded through hole 51, the clamping block 52. DETAILED DESCRIPTION

[0043] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0044] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “connecting” should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, or electrical connection or can communicate with each other; can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0045] Specifically, please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 The present application provides a kind of injection needle with sealing performance, the injection needle includes negative pressure seat 1, inner container needle seat 2 and several needle tubes 3;The inner container needle seat 2 is installed in the inner cavity of the negative pressure seat 1, the lower end face of the negative pressure seat 1 is equipped with several limit guide cylinders 11, the lower end face of the inner container needle seat 2 is equipped with several needle seat cylinders 21, the needle seat cylinder 21 is connected with the limit guide cylinder 11 one by one, the needle tube 3 is arranged in the needle seat cylinder 21, the needle tube 3 protrudes from the lower end face of the negative pressure seat 1 by passing through the limit guide cylinder 11.

[0046] Please refer to Figure 9 , Figure 10 , Figure 14 The limit guide cylinder 11 includes upper end sealing cavity 111, middle part sealing cavity 112 and lower end sealing cavity 113, the inner diameter of the upper end sealing cavity 111 is greater than the inner diameter of the middle part sealing cavity 112, the inner diameter of the middle part sealing cavity 112 is greater than the inner diameter of the lower end sealing cavity 113, the inner diameter of the lower end sealing cavity 113 is equal to the outer diameter of the needle tube 3, and the lower end sealing cavity 113 is sealingly connected with the needle tube 3;The needle seat cylinder 21 includes upper end cylinder 211, middle part cylinder 212 and lower end cylinder 213, the outer diameter of the upper end cylinder 211 is greater than the outer diameter of the middle part cylinder 212, the outer diameter of the middle part cylinder 212 is greater than the outer diameter of the lower end cylinder 213, the upper end cylinder 211 is located at the upper edge opening position of the upper end sealing cavity 111, the middle part cylinder 212 is sealingly arranged in the upper end sealing cavity 111, and the lower end cylinder 213 is sealingly arranged in the middle part sealing cavity 112.

[0047] The application realizes the stepped sealing connection of the limiting guide cylinder 11 and the needle seat cylinder 21, which can improve the sealing effect of the injection needle, and the multi-stage sealing connection mode can prevent the transparent beauty liquid from flowing back to the upper end of the inner cavity of the negative pressure seat 1.

[0048] The upper end sealing cavity 111, the middle sealing cavity 112 and the lower end sealing cavity 113 constitute a needle hole. The needle tube 3 is arranged at a specified height of the needle hole and is fixed by an environmentally friendly quick-drying glue.

[0049] Please refer to Figure 9 The upper end sealing cavity 111, the middle sealing cavity 112 and the lower end sealing cavity 113 are smoothly connected, the upper end cylinder 211, the middle cylinder 212 and the lower end cylinder 213 are smoothly connected, the transition cavity surface between the upper end sealing cavity 111 and the middle sealing cavity 112 is matched with the transition surface between the middle cylinder 212 and the lower end cylinder 213 in shape; when the needle seat cylinder 21 extends into the bottom of the limiting guide cylinder 11, the transition surface and the transition cavity surface are sealingly matched.

[0050] Further, the outer side surface of the needle seat cylinder 21 is gap-fitted with the inner side surface of the limiting guide cylinder 11, and the gap of the gap-fitting is in the range of 0-0.02mm.

[0051] Further, the outer side surface of the needle seat cylinder 21 is interference-fitted with the inner side surface of the limiting guide cylinder 11, and the interference amount of the interference-fitting is in the range of 0-0.15mm.

[0052] Further, the upper edge opening of the upper end sealing cavity 111 is a flexible and elastic thin-walled structure, the inner side of the upper edge opening of the upper end sealing cavity 111 is provided with a ring buckle structure 12, the ring buckle structure 12 is interference-fitted with the middle cylinder 212, and the interference amount of the interference-fitting is in the range of 0-0.15mm.

[0053] Please refer to Figure 11 The ring buckle structure 12 is a right-angle type ring buckle, the right-angle side of the right-angle type ring buckle is flush with the upper edge opening of the upper end sealing cavity 111, and the inner diameter of the right-angle type ring buckle gradually increases from the upper edge opening of the upper end sealing cavity 111 to the side of the middle sealing cavity 112; or,

[0054] Please refer to Figure 12, the ring buckle structure 12 is a rhombus type ring buckle, the upper end of the rhombus type ring buckle is flush with the upper edge of the upper end sealing cavity 111, the middle part of the rhombus type ring buckle is provided with a turning point, the inner diameter of the rhombus type ring buckle gradually decreases from the upper edge of the upper end sealing cavity 111 to the turning point, and the inner diameter of the rhombus type ring buckle gradually increases from the turning point to the side of the middle part sealing cavity 112; or,

[0055] Please refer to Figure 13 , the ring buckle structure 12 is an arc type ring buckle, the upper end of the arc type ring buckle is flush with the upper edge of the upper end sealing cavity 111, and the inner diameter of the arc type ring buckle is arc-shaped and gradually increases and then decreases from the upper edge of the upper end sealing cavity 111 to the side of the middle part sealing cavity 112.

[0056] Further, the outer side of the middle part cylinder 212 is provided with a sealing protruding structure 22, and the sealing protruding structure 22 is located at the position adjacent to the lower end cylinder 213 of the middle part cylinder 212.

[0057] Please refer to Figure 15 , the sealing protruding structure 22 is a right angle type protrusion, the right angle side of the right angle type protrusion is flush with the lower edge of the middle part cylinder 212, and the outer diameter of the right angle type protrusion gradually decreases from the lower edge of the middle part cylinder 212 to the side of the upper end cylinder 211; or,

[0058] Please refer to Figure 16 , the sealing protruding structure 22 is a rhombus type protrusion, the lower end of the rhombus type protrusion is flush with the lower edge of the middle part cylinder 212, the middle part of the rhombus type protrusion is provided with a protruding point, the outer diameter of the rhombus type protrusion gradually increases from the lower edge of the middle part cylinder 212 to the protruding point, and the outer diameter of the rhombus type protrusion gradually decreases from the protruding point to the side of the upper end cylinder 211; or,

[0059] Please refer to Figure 17 , the sealing protruding structure 22 is an arc type protrusion, the upper end of the arc type protrusion is flush with the lower edge of the middle part cylinder 212, and the outer diameter of the arc type protrusion is arc-shaped and gradually increases and then decreases from the lower edge of the middle part cylinder 212 to the side of the upper end cylinder 211.

[0060] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 18 , Figure 19 , Figure 20The injection needle further comprises a cone seat 4 and an adjusting seat 5, the inside of the cone seat 4 is provided with a hollow liquid guide pipe 41, the bottom surface of the cone seat 4 is provided with a distribution cavity 42, the distribution cavity 42 is connected with the needle seat cylinder 21 one by one, and the top of the needle tube 3 is communicated to the distribution cavity 42; the center of the adjusting seat 5 is provided with a threaded through hole 51, the outside of the cone seat 4 is provided with an external thread circular platform 43, the external thread circular platform 43 is threadedly connected with the threaded through hole 51, a plurality of clamping blocks 52 are arranged on the peripheral wall surface of the adjusting seat 5 in a ring direction, the outside of the negative pressure seat 1 is provided with a ring eaves body 13, and the adjusting seat 5 is clamped on the ring eaves body 13 through the clamping blocks 52.

[0061] Preferably, the threaded through hole 51 is provided with an inner double thread, the external thread circular platform 43 is provided with an outer double thread, and the outer double thread is matched with the inner double thread when the cone seat 4 is matched with the adjusting seat 5.

[0062] Please refer to Figure 5 , Figure 6 , Figure 7 , Figure 8 The top of the inner liner needle seat 2 is further provided with a plurality of positioning bosses 23, the positioning bosses 23 are arranged at intervals with the needle seat cylinder 21, the bottom surface of the cone seat 4 is provided with a plurality of limiting grooves, and the positioning bosses 23 are connected with the limiting grooves one by one.

[0063] Please refer to Figure 20 The bottom surface edge of the cone seat 4 is provided with a guide groove 44, the inner groove edge of the inner liner needle seat 2 is provided with a guide positioning rib 24, the guide positioning rib 24 is fixed in the guide groove 44 to realize the connection of the cone seat 4 and the inner liner needle seat 2. When the cone seat 4 is matched with the inner liner needle seat 2, the guide groove 44 falls to the specified position through the guide positioning rib 24.

[0064] The injection needle provided by the embodiment has sealing performance, the injection needle comprises a negative pressure seat 1, an inner liner needle seat 2 and a plurality of needle tubes 3, the lower end surface of the negative pressure seat 1 is provided with a plurality of limiting guide cylinders 11, the lower end surface of the inner liner needle seat 2 is provided with a plurality of needle seat cylinders 21, the needle seat cylinders 21 are connected with the limiting guide cylinders 11 one by one, the limiting guide cylinders 11 comprise an upper end sealing cavity 111, a middle part sealing cavity 112 and a lower end sealing cavity 113, the needle seat cylinders 21 comprise an upper end cylinder 211, a middle part cylinder 212 and a lower end cylinder 213, the limiting guide cylinders 11 and the needle seat cylinders 21 are connected in a stepped and sealed manner, the sealing effect of the injection needle can be improved, and the multi-stage sealing connection mode can avoid the transparent beauty liquid from flowing back to the upper end of the inner cavity of the negative pressure seat 1.

[0065] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0066] The above has carried out the detailed introduction to the injection needle with sealing performance provided by the embodiment of the application, the principle and implementation mode of the application are described by applying specific examples in this paper, the above embodiment is only used for helping understanding the technical scheme of the application and its core idea; the ordinary skilled in the art should understand that: it can still modify the technical scheme recorded by the foregoing each embodiment, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical scheme deviate from the scope of the technical scheme of the embodiments of the application.

Claims

1. A sealed performance injection needle, characterized in that, The injection needle comprises a negative pressure seat, an inner container needle seat and a plurality of needle tubes; the inner container needle seat is installed in the inner cavity of the negative pressure seat, the lower end face of the negative pressure seat is provided with a plurality of limiting guide cylinders, the lower end face of the inner container needle seat is provided with a plurality of needle seat cylinders, the needle seat cylinders are connected with the limiting guide cylinders one by one, the needle tubes are arranged in the needle seat cylinders, the needle tubes protrude from the lower end face of the negative pressure seat through the limiting guide cylinders; the limiting guide cylinder comprises an upper end sealing cavity, a middle part sealing cavity and a lower end sealing cavity, the inner diameter of the upper end sealing cavity is larger than the inner diameter of the middle part sealing cavity, the inner diameter of the middle part sealing cavity is larger than the inner diameter of the lower end sealing cavity, the inner diameter of the lower end sealing cavity is equal to the outer diameter of the needle tube, and the lower end sealing cavity is sealingly connected with the needle tube; the needle seat cylinder comprises an upper end cylinder, a middle part cylinder and a lower end cylinder, the outer diameter of the upper end cylinder is larger than the outer diameter of the middle part cylinder, the outer diameter of the middle part cylinder is larger than the outer diameter of the lower end cylinder, the upper end cylinder is located at the upper edge opening position of the upper end sealing cavity, the middle part cylinder is sealingly arranged in the upper end sealing cavity, and the lower end cylinder is sealingly arranged in the middle part sealing cavity.

2. The sealed injection needle of claim 1, wherein, The upper end sealing cavity, the middle part sealing cavity and the lower end sealing cavity are smoothly and transitionally connected, the upper end cylinder, the middle part cylinder and the lower end cylinder are smoothly and transitionally connected, the transition cavity surface between the upper end sealing cavity and the middle part sealing cavity is matched with the transition curved surface between the middle part cylinder and the lower end cylinder; when the needle seat cylinder extends into the bottom of the limiting guide cylinder, the transition curved surface is sealingly matched with the transition cavity surface.

3. The sealed injection needle of claim 1, wherein, The outer side surface of the needle seat cylinder is gap matched with the inner side surface of the limiting guide cylinder, and the gap of the gap matching is in the range of 0-0.02 mm.

4. The sealed injection needle of claim 1, wherein, The outer side surface of the needle seat cylinder is interference matched with the inner side surface of the limiting guide cylinder, and the interference amount of the interference matching is in the range of 0-0.15 mm.

5. The sealed injection needle of claim 1, wherein, The upper edge opening of the upper end sealing cavity is a flexible and elastic thin-walled structure, the inner side of the upper edge opening of the upper end sealing cavity is provided with a ring buckle structure, the ring buckle structure is interference matched with the middle part cylinder, and the interference amount of the interference matching is in the range of 0-0.15 mm.

6. The sealed injection needle of claim 5, wherein, The ring buckle structure is a right-angle type ring buckle, the right-angle side of the right-angle type ring buckle is flush with the upper edge opening of the upper end sealing cavity, and the inner diameter of the right-angle type ring buckle gradually increases from the upper edge opening of the upper end sealing cavity to the side towards the middle part sealing cavity; or The ring buckle structure is a diamond type ring buckle, the upper end of the diamond type ring buckle is flush with the upper edge opening of the upper end sealing cavity, the middle part of the diamond type ring buckle is provided with a turning point, the inner diameter of the diamond type ring buckle gradually decreases from the upper edge opening of the upper end sealing cavity to the turning point, and the inner diameter of the diamond type ring buckle gradually increases from the turning point to the side towards the middle part sealing cavity; or The ring buckle structure is an arc type ring buckle, the upper end of the arc type ring buckle is flush with the upper edge opening of the upper end sealing cavity, and the inner diameter of the arc type ring buckle is arc-shaped and gradually decreases and then increases from the upper edge opening of the upper end sealing cavity to the side towards the middle part sealing cavity.

7. The sealed injection needle of claim 1, wherein, The outer side of the middle cylinder is provided with a sealing protruding structure, which is located at the position adjacent to the lower end cylinder of the middle cylinder.

8. The sealed injection needle of claim 7, wherein, The sealing protruding structure is a right-angle protruding structure, the right-angle edge of the right-angle protruding structure is flush with the lower edge of the middle cylinder, and the outer diameter of the right-angle protruding structure gradually decreases from the lower edge of the middle cylinder to the side towards the upper end cylinder; or, The sealing protruding structure is a diamond-shaped protruding structure, the lower end of the diamond-shaped protruding structure is flush with the lower edge of the middle cylinder, the middle part of the diamond-shaped protruding structure is provided with a protruding point, the outer diameter of the diamond-shaped protruding structure gradually increases from the lower edge of the middle cylinder to the protruding point, and the outer diameter of the diamond-shaped protruding structure gradually decreases from the protruding point to the side towards the upper end cylinder; or, The sealing protruding structure is an arc-shaped protruding structure, the upper end of the arc-shaped protruding structure is flush with the lower edge of the middle cylinder, and the outer diameter of the arc-shaped protruding structure is arc-shaped and gradually increases and then decreases from the lower edge of the middle cylinder to the side towards the upper end cylinder.

9. The sealed injection needle of claim 1, wherein, The injection needle further comprises a cone seat and an adjusting seat, the inside of the cone seat is provided with a hollow liquid guide pipe, the bottom surface of the cone seat is provided with a distribution cavity, the distribution cavity is connected with the needle seat cylinder one by one, and the top of the needle tube is communicated to the distribution cavity; the center of the adjusting seat is provided with a threaded through hole, the outer side of the cone seat is provided with an outer threaded circular table, the outer threaded circular table is threadedly connected with the threaded through hole, a plurality of clamping blocks are arranged on the peripheral wall surface of the adjusting seat in a ring direction, the outer part of the negative pressure seat is provided with a ring eave body, and the adjusting seat is clamped on the ring eave body through the clamping blocks.

10. The sealed injection needle of claim 9, wherein the needle hub is formed of a material that is more rigid than the needle cannula. The top of the inner container needle seat is further provided with a plurality of positioning bosses, the positioning bosses are arranged at intervals with the needle seat cylinder, the bottom surface of the cone seat is provided with a plurality of limiting grooves, and the positioning bosses are connected with the limiting grooves one by one.

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