Needleless injector

Abstract

The utility model relates to medical instrument technical field discloses a needleless injector, including main part, needleless injection head and liquid outlet valve, the main part is equipped with transition chamber, liquid outlet chamber and power chamber, transition chamber is used for pre -filling liquid medicine, power chamber is coaxial with transition chamber, liquid outlet chamber is established, and the cross section area of transition chamber is less than the cross section area of power chamber, the needleless injection head is equipped with injection chamber, and the injection micropore that communicates injection chamber with outside, the one end of needleless injection head away from injection micropore stretches into liquid outlet chamber, and will liquid outlet valve and set up in liquid outlet chamber, liquid outlet valve includes first valve body and first valve core, the one end of first valve body near transition chamber is sealed with liquid outlet chamber arrangement, first valve body is equipped with first guide chamber, the outer periphery of first valve body is equipped with first through -hole, the outer periphery of first valve body and the inside wall of liquid outlet chamber have first gap, first gap and injection chamber, first through -hole are communicated, first valve core can reciprocate in first guide chamber, to make transition chamber and first through -hole communicate or disconnect. The needleless injector of the utility model is simple structure, and the processing cost is low, and the stable injection effect.

Description

Technical Field

[0001] This utility model relates to the field of medical device technology, and in particular to a needleless injector. Background Technology

[0002] Needle-free injectors eliminate the need for needles. Instead, they are medical devices that inject liquid medications into the patient's skin, subcutaneous tissue, or muscle through a micro-orifice at the tip by applying high pressure. This significantly reduces injection pain and psychological burden.

[0003] Existing needleless injectors have a relatively complex structure. Acceleration of the liquid usually relies on the complex curved structure of the needleless injection head. Furthermore, the body needs to form a partition with multiple through holes between two chambers. Each connector relies on the external thread structure at the end of the body for locking. These structures increase the difficulty and cost of product manufacturing, and the stability of the injection effect is difficult to guarantee.

[0004] Therefore, it is necessary to provide a needle-free injector that is simple in structure, low in processing cost, and has more stable injection effect. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a needle-free injector that has a simple structure, low processing cost, and stable injection effect.

[0006] To solve the above-mentioned technical problems, this utility model provides a needleless injector, including a main body, a needleless injection head, and a dispensing valve.

[0007] The main body is provided with a transition cavity, a liquid outlet cavity and a power cavity. The transition cavity is used for pre-filling with liquid medicine. The power cavity is coaxially arranged with the transition cavity and the liquid outlet cavity, and the cross-sectional area of ​​the transition cavity is smaller than that of the power cavity.

[0008] The needleless injection head is provided with an injection chamber and an injection micro-hole that connects the injection chamber to the outside. The end of the needleless injection head away from the injection micro-hole extends into the liquid outlet chamber, and the liquid outlet valve is placed against the liquid outlet chamber.

[0009] The dispensing valve includes a first valve body and a first valve core. The end of the first valve body near the transition cavity is sealed to the dispensing cavity. The first valve body is provided with a first guide cavity. The outer peripheral surface of the first valve body is provided with a first through hole. The outer peripheral surface of the first valve body has a first gap with the inner wall of the dispensing cavity. The first gap communicates with the injection cavity and the first through hole. The first valve core can reciprocate within the first guide cavity to make the transition cavity communicate with or disconnect from the first through hole.

[0010] As an improvement to the above scheme, the cross-sectional area of ​​the transition cavity is smaller than the cross-sectional area of ​​the first guide cavity near the end of the transition cavity.

[0011] As an improvement to the above solution, the first through hole and the end face of the first valve body near the transition cavity are provided with a preset distance.

[0012] As an improvement to the above solution, the first guide cavity is axially through.

[0013] As an improvement to the above solution, it also includes an inlet valve and an inlet connector. The main body is also provided with an inlet chamber that crosses and communicates with the transition chamber. The inlet connector is provided with an inlet channel that communicates with the inlet chamber. The inlet connector extends into the inlet chamber so that the inlet valve is pressed against the inlet chamber.

[0014] As an improvement to the above solution, a push rod is also included, which is slidably disposed in the power chamber. The push rod reciprocates in the power chamber to drive the liquid medicine in the transition chamber into the outlet chamber, or the liquid medicine in the inlet chamber into the transition chamber.

[0015] As an improvement to the above solution, the inlet valve includes a second valve body and a second valve core. The second valve body has a second guide cavity, and the outer peripheral surface of the second valve body has a through second hole. The outer peripheral surface of the middle part of the second valve body has a second gap with the inner wall of the inlet cavity. The second gap communicates with the transition cavity and the second through hole. The second valve core reciprocates in the second guide cavity to make the inlet channel communicate with or disconnect from the second through hole.

[0016] As an improvement to the above solution, the power chamber includes a first power chamber and a second power chamber. The first power chamber connects the second power chamber and the transition chamber. The cross-sectional area of ​​the first power chamber is smaller than that of the second power chamber. The first power chamber has a first inclined surface at one end near the transition chamber and a first protrusion on the outer periphery of the first inclined surface. The end of the push rod opposite to the transition chamber has a second inclined surface. The angle between the second inclined surface and the axial direction is smaller than the angle between the first inclined surface and the axial direction.

[0017] As an improvement to the above solution, the needleless injection head includes a first chamber and a second chamber. The first chamber is located in the direction away from the injection micro-hole in the second chamber. The cross-sectional areas of the first chamber and the second chamber are constant, and the cross-sectional area of ​​the first chamber is greater than that of the second chamber. When the first valve core moves to make the transition chamber communicate with the first through hole, it extends into the second chamber.

[0018] As an improvement to the above solution, the needleless injection head further includes a third chamber connected to the injection micro-orifice, the second chamber connecting the first chamber and the third chamber, and the cross-sectional area of ​​the third chamber gradually increases in the direction away from the injection micro-orifice.

[0019] Implementing this utility model has the following beneficial effects:

[0020] This utility model discloses a needle-free injector. By coaxially arranging the power chamber, transition chamber, and liquid outlet chamber of the main body, the cross-sectional area of ​​the transition chamber is smaller than that of the power chamber. Simultaneously, the end of the first valve body near the transition chamber is sealed to the liquid outlet chamber, creating a first gap between the outer circumferential surface of the first valve body and the inner wall of the liquid outlet chamber, which communicates with the injection chamber and the first through hole. During injection, the pre-filled liquid in the transition chamber more easily and rapidly pushes the first valve core to move within the first guide chamber of the first valve body, resulting in a higher initial velocity of the liquid and thus increasing the injection speed. The end of the needle-free injection head furthest from the injection micro-orifice extends into the liquid outlet chamber, and the entire liquid outlet valve is positioned against the liquid outlet chamber, simplifying the assembly structure. Furthermore, the main body does not require a partition with multiple through holes, significantly reducing molding difficulty. The injection speed no longer solely depends on the structure of the needle-free injection head, allowing for a simpler needle-free injection head design, reduced manufacturing costs, and improved injection stability. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of an embodiment of the needle-free injector of this utility model;

[0022] Figure 2 yes Figure 1 A sectional view of the main body through the plane of symmetry;

[0023] Figure 3 yes Figure 1 A sectional view through the plane of symmetry;

[0024] Figure 4 yes Figure 3 A schematic diagram of the structure in the liquid extraction state;

[0025] Figure 5 yes Figure 3 A schematic diagram of the injection state structure;

[0026] Figure 6 yes Figure 3 A magnified structural diagram of part A;

[0027] Figure 7 yes Figure 3 A schematic diagram of the enlarged structure of part B;

[0028] Figure 8 This is a schematic diagram of the structure of a needle-free injection head;

[0029] Figure 9 This is a schematic diagram of the structure of the first valve body;

[0030] Figure 10 This is a sectional view of the first valve body;

[0031] Figure 11 yes Figure 9 Side view. Detailed Implementation

[0032] To make the objectives, technical solutions and advantages of this utility model clearer, the utility model will be described in further detail below with reference to the accompanying drawings.

[0033] like Figures 1 to 11 As shown, this utility model discloses an embodiment of a needleless injector, including a main body 1, a needleless injection head 2, and a dispensing valve 3. The main body 1 has a transition chamber 11, a dispensing chamber 12, and a power chamber 13. The transition chamber 11 is used for pre-filling with medication. The power chamber 13 is coaxially arranged with the transition chamber 11 and the dispensing chamber 12, and the cross-sectional area of ​​the transition chamber 11 is smaller than the cross-sectional area of ​​the power chamber 13. The needleless injection head 2 has an injection chamber 21 and an injection micro-hole 22 connecting the injection chamber 21 to the outside. One end of the needleless injection head 2 away from the injection micro-hole 22 extends into the dispensing chamber 12, and the dispensing valve 3 is abutted against it. In the liquid outlet chamber 12, the liquid outlet valve 3 includes a first valve body 31 and a first valve core 32. The end of the first valve body 31 near the transition chamber 11 is sealed to the liquid outlet chamber 12. The first valve body 31 is provided with a first guide chamber 311. The outer peripheral surface of the first valve body 31 is provided with a first through hole 312. The outer peripheral surface of the first valve body 31 and the inner wall of the liquid outlet chamber 12 have a first gap a. The first gap a communicates with the injection chamber 21 and the first through hole 312. The first valve core 32 can reciprocate within the first guide chamber 311 so that the transition chamber 11 communicates with or disconnects from the first through hole 312.

[0034] In this embodiment, the power chamber 13 of the main body 1 is coaxially arranged with the transition chamber 11 and the liquid outlet chamber 12, so that the cross-sectional area of ​​the transition chamber 11 is smaller than that of the power chamber 13. At the same time, the end of the first valve body 31 near the transition chamber 11 is sealed to the liquid outlet chamber 12, so that the outer peripheral surface of the first valve body 31 and the inner wall of the liquid outlet chamber 12 have a first gap a that communicates with the injection chamber 21 and the first through hole 312. During injection, the pre-filled liquid in the transition chamber 11 can more easily push the first valve core 32 at high speed in the first valve body 31. The movement within the first guide cavity 311 of the needleless injection head 1 increases the initial velocity of the liquid, thus improving the injection speed. The end of the needleless injection head 2 away from the injection micro-hole 22 extends into the liquid outlet cavity 12, and the entire liquid outlet valve 3 is placed against the liquid outlet cavity 12. This simplifies the assembly structure. At the same time, the body 1 does not need to have a partition with multiple through holes inside, which greatly reduces the molding difficulty. The liquid injection speed no longer depends solely on the structure of the needleless injection head 2. The needleless injection head 2 can be designed to be simpler, reducing manufacturing costs and improving the stability of the injection effect.

[0035] In this embodiment, the cross-sectional area of ​​the transition cavity 11 is preferably set to be smaller than the cross-sectional area of ​​the first guide cavity 311 near the end of the transition cavity 11. At the instant the transition cavity 11 communicates with the first guide cavity 311, the pressure acting on the surface of the first valve core 32 increases with the increase in the contact area with the liquid medication, helping to accelerate the rapid movement of the first valve core 32 to the position where the transition cavity 11 communicates with the first through hole 312, thereby accelerating the injection speed of the liquid medication.

[0036] In this embodiment, the first guide cavity 311 is preferably axially through. When the first valve core 32 moves within the first guide cavity 311, it can extend into the injection cavity 21 of the needleless injection head 2. The movement space of the first valve core 32 is no longer limited to the first valve body 31, which helps to reduce the volume of the first valve body 31 and the volume of the needleless injector. At the same time, the extension of the first valve core 32 into the injection cavity 21 of the needleless injection head 2 can reduce the flow cross-sectional area of ​​the injection cavity 21, which can help to increase the flow rate at that point.

[0037] In this embodiment, the first through hole 312 and the end face of the first valve body 31 near the transition cavity 11 are provided with a preset distance. Before the liquid medicine enters the injection cavity 21 through the first through hole 312 and the first gap a, the first valve core 32 can be inserted into the injection cavity 21 of the needleless injection head 2, so as to reduce the flow cross-sectional area of ​​the injection cavity 21 before the liquid medicine flows into the injection cavity 21, so that the flow rate in the injection cavity 21 is increased more timely.

[0038] The needleless injection head 2 in this embodiment includes a first chamber 211 and a second chamber 212. The first chamber 211 is located in the direction away from the injection micro-hole 22 in the second chamber 212. The cross-sectional areas of the first chamber 211 and the second chamber 212 are constant, and the cross-sectional area of ​​the first chamber 211 is larger than that of the second chamber 212. When the first valve core 32 moves to make the transition chamber 11 communicate with the first through hole 312, it extends into the second chamber 212, so that the flow cross-sectional area of ​​the drug liquid flowing through the second chamber 212 becomes drastically smaller, which helps to promote the increase of flow rate. When the needleless injection head 2 is assembled with the main body 1, the first chamber 211 of the needleless injection head 2 is located inside the main body 1, and the second chamber 212 is at least partially located inside the main body 1. The first valve core 32 can extend into the first chamber 211 and the second chamber 212 of the needleless injection head 2. On the one hand, this realizes the change of the flow cross-sectional area inside the needleless injection head 2 to increase the flow rate. On the other hand, it allows the needleless injection head 2 to have a longer section inserted into the liquid outlet chamber 12. The two are preferably interference fit, which simplifies the assembly structure.

[0039] The needle-free injection head 2 also includes a third chamber 213 connected to the injection micro-orifice 22. The second chamber 212 connects the first chamber 211 and the third chamber 213. The cross-sectional area of ​​the third chamber 213 gradually increases in the direction away from the injection micro-orifice 22, while the cross-sectional area of ​​the injection micro-orifice 22 remains constant. The liquid medicine flowing through the third chamber 213 will be accelerated again and ejected through the injection micro-orifice 22.

[0040] The constant cross-sectional area of ​​the injection micro-orifice 22 facilitates processing and molding, resulting in more stable injection effects for each product. Furthermore, the constant cross-sectional area of ​​the injection micro-orifice 22 in this embodiment allows the front end of the needle-free injection head 2 to be positioned as a positioning plane 23. The injection micro-orifice 22 is formed on this positioning plane 23, whose cross-sectional area is close to that of the second chamber 212. During injection, this positioning plane 23 directly contacts the human skin, eliminating the need for a separate support cover and further simplifying the assembly structure and reducing material costs.

[0041] In addition, the needleless injection head 2 is provided with a positioning boss 24 and a first sealing groove on the side of the positioning boss 24 away from the injection micro-hole 22. A fifth sealing ring is provided in the first sealing groove. When the needleless injection head 2 is inserted into the liquid outlet chamber 12, the fifth sealing ring seals with the inner wall of the liquid outlet chamber 12, and the positioning boss 24 abuts against the end face of the main body 1 where the liquid outlet chamber 12 is opened. The positioning boss 24 of the needleless injection head 2 is set close to the third chamber 213 to reduce the volume of the syringe and to provide auxiliary support during injection.

[0042] Specifically, the first valve body 31 has two first protruding rings 313 on its outer peripheral surface near the transition cavity 11, and a first groove between the two first protruding rings 313. A first sealing ring is provided in the first groove, and the first sealing ring is in sealing contact with the inner sidewall of the liquid outlet cavity 12. The end of the first valve body 31 away from the transition cavity 11 has a second protruding ring 314 and a first liquid guiding groove 315. The second protruding ring 314 abuts against the needleless injection head 2, and the first liquid guiding groove 315 passes through the second protruding ring 314 and connects the injection cavity 21 and the first gap a, so that the liquid in the first gap a can flow to the injection cavity 21.

[0043] The first valve core 32 includes a first push rod 321 and a first elastic element 322. The two ends of the first elastic element 322 abut against the first valve body 31 and the first push rod 321, respectively, providing elastic force to the first push rod 321. This allows the first push rod 321 to move towards the transition cavity 11 to isolate the transition cavity 11 from the liquid outlet cavity 12. A second sealing ring is provided at one end of the first push rod 321 near the transition cavity 11, sealingly contacting the inner wall of the first guide cavity 311.

[0044] In this embodiment, the power chamber 13 is coaxially arranged with the transition chamber 11, the liquid outlet chamber 12, and the injection micro-orifice 22. The main body 1 also has a liquid inlet chamber 14 that crosses and communicates with the transition chamber 11. The liquid inlet chamber 14 is used to inject liquid medicine into the transition chamber 11. The liquid inlet chamber 14 is provided with a liquid inlet valve 4 and a liquid inlet connector 5 connected thereto. The liquid inlet connector 5 has a liquid inlet channel 51 that communicates with the liquid inlet chamber 14. The liquid inlet connector 5 extends into the liquid inlet chamber 14 to abut the liquid inlet valve 4 against the liquid inlet chamber 14. In this embodiment, the liquid inlet connector 5 is a Luer connector, which has a sixth sealing ring that seals against the inner wall of the liquid inlet chamber 14.

[0045] In this embodiment, the inlet valve 4 and the outlet valve preferably adopt the same structure, which facilitates assembly. Specifically, the inlet valve 4 includes a second valve body 41 and a second valve core 42. The second valve body 41 has a second guide cavity 411, and the outer peripheral surface of the second valve body 41 has a through second through hole 412. The outer peripheral surface of the middle part of the second valve body 41 has a second gap b with the inner sidewall of the inlet cavity 14. The second gap b communicates with the transition cavity 11 and the second through hole 412. The second valve core 42 reciprocates within the second guide cavity 411 to connect or disconnect the inlet channel 51 from the second through hole 412.

[0046] Specifically, the second valve body 41 has two third protruding rings on its outer circumferential surface near the liquid inlet channel 51, and a second groove between the two third protruding rings. A third sealing ring is provided in the second groove, and the third sealing ring makes sealing contact with the inner circumferential wall of the liquid inlet chamber 14. At the end of the second valve body 41 away from the liquid inlet channel 51, a fourth protruding ring and a second liquid guide groove are provided. The second liquid guide groove passes through the fourth protruding ring and communicates with the third gap, allowing the liquid in the third gap to flow to the end of the liquid inlet chamber 14 connected to the transition chamber 11. The second valve core 42 includes a second push rod 421 and a second elastic element 422. The two ends of the second elastic element 422 abut against the second valve body 41 and the second push rod 421, respectively, providing elastic force to the second push rod 421, enabling the second push rod 421 to move towards the liquid inlet channel 51 to isolate the transition chamber 11 from the liquid inlet channel 51. The second push rod 421 is provided with a fourth sealing ring at one end near the transition cavity 11, which is in sealing contact with the inner sidewall of the first guide cavity 311 in the circumferential direction.

[0047] The main body 1 also has a liquid pushing rod 6 in the power chamber 13. The liquid pushing rod 6 is slidably disposed in the power chamber 13. The liquid pushing rod 6 moves back and forth in the power chamber 13 to drive the liquid in the transition chamber 11 into the outlet chamber 12, or the liquid in the inlet chamber 14 into the transition chamber 11.

[0048] The power chamber 13 specifically includes a first power chamber 131 and a second power chamber 132. The first power chamber 131 connects the second power chamber 132 and the transition chamber 11. The cross-sectional area of ​​the first power chamber 131 is smaller than that of the second power chamber 132. The first power chamber 131 has a first inclined surface 133 at one end near the transition chamber 11 and a first protrusion on the outer periphery of the first inclined surface 133. The end of the push rod 6 opposite to the transition chamber 11 has a second inclined surface 61. The angle between the second inclined surface 61 and the axial direction is smaller than the angle between the first inclined surface 133 and the axial direction. Thus, during the movement of the push rod 6, the contact surface between the push rod 6 and the liquid medicine can be increased, so that the liquid medicine in the power chamber 13 can flow to the transition chamber 11 more quickly.

[0049] The operation of the needleless injector according to the embodiments of this utility model will be described below with reference to the accompanying drawings.

[0050] Liquid extraction status:

[0051] like Figure 4 As shown, the push rod 6 moves to the right, creating a negative pressure in the transition chamber 11. The first push rod 321 of the first valve core 32 moves to the right under the suction force of the transition chamber 11 and the force of the first elastic element 322 until it is limited by the main body 1. At the same time, the second push rod 421 of the second valve core 42 moves downward under the negative pressure, overcoming the elastic force of the second elastic element 422, until it is limited by the second valve body 41. The liquid medicine enters the transition chamber 11 through the second through hole 412 on the second valve body 41 and the second gap b.

[0052] Injection status:

[0053] like Figure 5 As shown, the push rod 6 moves to the left, pushing the liquid in the transition chamber 11 to gather to the left and creating a thrust on the first valve core 32. The first push rod 321 of the first valve core 32 moves to the left until it is limited by the first valve body 31. The liquid flows through the first through hole 312 of the first valve body 31 and is ejected through the injection micro-hole 22 of the needleless injection head 2. At the same time, the second push rod 421 of the second valve core 42 moves upward under the hydraulic action in the transition chamber 11 and the elastic force of the second elastic element 422 until it is limited by the Luer joint. At this time, the liquid cannot flow into the transition chamber 11 through the second through hole 412 of the second valve body 41.

[0054] In this embodiment, the main body 1 of the needleless injector is preferably made of medical-grade plastic, which makes the internal state of the needleless injector visible. Compared with metal materials, it reduces processing and material costs. The needleless injection head 2, liquid inlet connector 5, etc. are also preferably made of medical-grade plastic, so that they can be used as disposable consumables, avoiding repeated cleaning and sterilization operations, and avoiding the risk of cross-infection caused by improper repeated cleaning and sterilization operations.

[0055] The above-disclosed embodiment is merely a preferred embodiment of the present utility model and should not be construed as limiting the scope of the present utility model. Therefore, any equivalent variations made in accordance with the claims of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A needle-free injector, characterized in that, Includes the main body, needle-free injection head, and dispensing valve. The main body is provided with a transition cavity, a liquid outlet cavity and a power cavity. The transition cavity is used for pre-filling with liquid medicine. The power cavity is coaxially arranged with the transition cavity and the liquid outlet cavity, and the cross-sectional area of ​​the transition cavity is smaller than that of the power cavity. The needleless injection head is provided with an injection chamber and an injection micro-hole that connects the injection chamber to the outside. The end of the needleless injection head away from the injection micro-hole extends into the liquid outlet chamber, and the liquid outlet valve is placed against the liquid outlet chamber. The dispensing valve includes a first valve body and a first valve core. The end of the first valve body near the transition cavity is sealed to the dispensing cavity. The first valve body is provided with a first guide cavity. The outer peripheral surface of the first valve body is provided with a first through hole. The outer peripheral surface of the first valve body has a first gap with the inner wall of the dispensing cavity. The first gap communicates with the injection cavity and the first through hole. The first valve core can reciprocate within the first guide cavity to make the transition cavity communicate with or disconnect from the first through hole.

2. The needleless injector according to claim 1, characterized in that, The cross-sectional area of ​​the transition cavity is smaller than the cross-sectional area of ​​the first guide cavity near the end of the transition cavity.

3. The needleless injector according to claim 1, characterized in that, The first guide cavity is axially continuous.

4. The needleless injector according to claim 1, characterized in that, The first through hole and the end face of the first valve body near the transition cavity are provided with a preset distance.

5. The needleless injector according to claim 1, characterized in that, It also includes an inlet valve and an inlet connector. The main body is further provided with an inlet chamber that crosses and communicates with the transition chamber. The inlet connector is provided with an inlet channel that communicates with the inlet chamber. The inlet connector extends into the inlet chamber to press the inlet valve against the inlet chamber.

6. The needleless injector according to claim 5, characterized in that, It also includes a push rod, which is slidably disposed in the power chamber. The push rod reciprocates in the power chamber to drive the liquid medicine in the transition chamber into the outlet chamber, or the liquid medicine in the inlet chamber into the transition chamber.

7. The needleless injector according to claim 5 or 6, characterized in that, The inlet valve includes a second valve body and a second valve core. The second valve body has a second guide cavity and a through second hole on its outer peripheral surface. The outer peripheral surface of the middle part of the second valve body has a second gap with the inner wall of the inlet cavity. The second gap communicates with the transition cavity and the second through hole. The second valve core moves back and forth in the second guide cavity to make the inlet channel communicate or disconnect with the second through hole.

8. The needleless injector according to claim 1, characterized in that, The power chamber includes a first power chamber and a second power chamber. The first power chamber connects the second power chamber and the transition chamber. The cross-sectional area of ​​the first power chamber is smaller than that of the second power chamber. The first power chamber has a first inclined surface at one end near the transition chamber and a first protrusion on the outer periphery of the first inclined surface. The end of the push rod opposite to the transition chamber has a second inclined surface. The angle between the second inclined surface and the axial direction is smaller than the angle between the first inclined surface and the axial direction.

9. The needleless injector according to claim 1, characterized in that, The needleless injection head includes a first chamber and a second chamber. The first chamber is located in the direction away from the injection micro-hole in the second chamber. The cross-sectional areas of the first chamber and the second chamber are constant, and the cross-sectional area of ​​the first chamber is greater than that of the second chamber. When the first valve core moves to make the transition chamber communicate with the first through hole, it extends into the second chamber.

10. The needleless injector according to claim 9, characterized in that, The needle-free injection head also includes a third chamber connected to the injection micro-orifice. The second chamber connects the first chamber and the third chamber, and the cross-sectional area of ​​the third chamber gradually increases in the direction away from the injection micro-orifice.

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