Needleless injector

Abstract

The utility model relates to medical instrument technical field discloses a needleless injector, including liquid pass main part, needleless injection head and liquid outlet valve, liquid pass main part is equipped with liquid outlet chamber, transition chamber and power chamber, and is equipped with first piston in power chamber, needleless injection head is equipped with distribution chamber and at least two injection holes in, and injection hole intercommunication distribution chamber and outside, liquid outlet valve includes valve body and first valve core, and is equipped with axial through in valve body, and with distribution chamber opposite liquid flow channel, and the outer periphery of first valve core and the inside wall of liquid outlet chamber have first gap, and first valve core is equipped with first liquid guide groove in the end away from transition chamber, and first liquid guide groove sets up towards valve body opening, and with liquid flow channel, first gap intercommunication, and first valve core sets up in liquid outlet chamber one end close to transition chamber, and first valve core can along axial reciprocating movement with transition chamber in medicine liquid pressure change to make first gap and transition chamber communicate or disconnect. The utility model discloses a needleless injector, and the injection efficiency is high, and injection effect is stable.

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] Most needle-free injectors currently available are single-head injectors, which can only deliver a small dose per unit time, resulting in low injection efficiency. Otherwise, they may cause pain and discomfort to the human body.

[0004] Therefore, it is necessary to provide a needle-free injector with higher injection efficiency and 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 with high injection efficiency and stable injection effect.

[0006] To solve the above-mentioned technical problems, this utility model provides a needleless injector, including a liquid inlet body, a needleless injection head, and a liquid outlet valve. The liquid-conducting body is provided with a liquid outlet chamber, a transition chamber and a power chamber. The transition chamber is used for pre-filling with liquid medicine. The cross-sectional area of ​​the transition chamber is smaller than that of the liquid outlet chamber. The power chamber is provided with a first piston, which is connected to a power source. The needleless injection head has a dispensing cavity and at least two injection holes, the injection holes being connected to the dispensing cavity and the outside. The dispensing valve includes a valve body and a first valve core. The valve body is sealed to at least one of the liquid-passing body and the needle-free injection head. The valve body has an axially penetrating liquid passage opposite to the dispensing chamber. The outer peripheral surface of the first valve core has a first gap with the inner wall of the dispensing chamber. The end of the first valve core away from the transition chamber has a first liquid guide groove. The first liquid guide groove is disposed facing the opening of the valve body and is connected to the liquid passage and the first gap. The first valve core is disposed at the end of the dispensing chamber near the transition chamber. The first valve core can move axially back and forth as the pressure of the liquid in the transition chamber changes, so that the first gap communicates with or disconnects from the transition chamber.

[0007] As an improvement to the above solution, the valve body is provided with a first abutment cavity, the first abutment cavity is coaxially arranged with the liquid flow channel, the first abutment cavity is provided with a first elastic reset member, and the first valve core is provided with a second abutment cavity arranged opposite to the first abutment cavity, the first elastic reset member abutting against the second abutment cavity.

[0008] As an improvement to the above solution, the first valve core is provided with a first convex ring and a second convex ring at its two ends respectively. The first convex ring and the second convex ring both protrude outward from the outer peripheral surface of the first valve core and are adapted to the liquid outlet cavity. The first liquid guide groove axially penetrates the first convex ring and communicates with the second abutment cavity. The second convex ring is provided with a second liquid guide groove, which axially penetrates the second convex ring and communicates with the first gap.

[0009] As an improvement to the above solution, the end face of the first valve core opposite to the transition cavity is provided with a sealing groove, and a first sealing element for sealing the transition cavity is provided in the sealing groove.

[0010] As an improvement to the above scheme, the dispensing cavity includes a central cavity and guide grooves arranged radially from the central cavity. The injection holes are arranged in a circumferential array in the central cavity. The injection holes communicate with the central cavity through the corresponding guide grooves. The liquid flow channel is coaxially arranged with the central cavity.

[0011] As an improvement to the above solution, the needleless injection head is further provided with an assembly cavity, the assembly cavity is provided with a first plane, the dispensing cavity is opened on the first plane, and the cross-section of the guide groove is arc-shaped. The first plane abuts against the end face of the valve body, and the valve body is sealed with the assembly cavity.

[0012] As an improvement to the above solution, the injection port includes a first chamber, a second chamber, and a third chamber. The first chamber is connected to the outside, the second chamber connects the first chamber and the third chamber, and the third chamber is connected to the dispensing chamber. The cross-sectional areas of the first chamber and the third chamber are constant, and the cross-sectional area of ​​the first chamber is smaller than that of the third chamber. The cross-sectional area of ​​the second chamber gradually increases in the direction away from the first chamber.

[0013] As an improvement to the above solution, it also includes an inlet valve and an inlet connector. The liquid-conducting 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 valve includes a second valve core and a second elastic reset member. The outer peripheral surface of the second valve core has a second gap with the inner wall of the inlet chamber. The second gap communicates with the transition chamber. The side of the second valve core facing away from the inlet connector is provided with a third abutment cavity. The inlet chamber is provided with a fourth abutment cavity that is opposite to the third abutment cavity. The second elastic reset member abuts against the third abutment cavity and the fourth abutment cavity, which can drive the second valve core to move towards the inlet channel and disconnect the second gap from the inlet channel.

[0014] As an improvement to the above solution, the two ends of the second valve core are respectively provided with a third convex ring and a fourth convex ring. The third convex ring and the fourth convex ring are both provided to protrude outward from the outer peripheral surface of the second valve core and are adapted to the liquid inlet chamber. The end of the second valve core away from the transition chamber is provided with a third liquid guide groove. The third liquid guide groove axially penetrates the third convex ring and communicates with the third abutment chamber and the second gap. The fourth convex ring is provided with a fourth liquid guide groove. The fourth liquid guide groove axially penetrates the fourth convex ring and communicates with the second gap.

[0015] As an improvement to the above solution, the power chamber, the transition chamber, and the liquid outlet chamber are coaxially arranged. The cross-sectional area of ​​the transition chamber is smaller than that of the power chamber. The first piston reciprocates within the power chamber to drive the liquid in the transition chamber into the liquid outlet chamber, or the liquid in the inlet channel into the transition chamber.

[0016] Implementing this utility model has the following beneficial effects: This utility model discloses a needleless injector. The needleless injection head has a dispensing cavity and at least two injection holes. The cross-sectional area of ​​the transition cavity of the liquid-conducting body is set to be smaller than the cross-sectional area of ​​the outlet cavity. A first valve core is disposed in the outlet cavity, and the outer peripheral surface of the first valve core has a first gap with the inner wall of the outlet cavity. The end of the first valve core away from the transition cavity has a first guide groove facing the valve body opening. This first guide groove connects the first gap with a liquid flow channel on the valve body, which is opposite to the dispensing cavity of the needleless injection head. The needleless injection head has at least two injection holes connecting the dispensing cavity to the outside. When the first piston in the power cavity is driven by a power source to compress the liquid in the transition cavity, the first valve core moves axially at the end of the outlet cavity near the transition cavity, specifically moving away from the transition cavity. When the valve core is not in contact with the valve body, the liquid medicine in the transition chamber enters the outlet chamber and passes through the first gap. Part of it enters the liquid flow channel through the first guide groove, and another part enters the liquid flow channel through the gap between the first valve core and the first valve body. The liquid medicine entering the liquid flow channel has a larger flow rate and a relatively smaller flow velocity, which helps to fill the distribution chamber and each injection hole with liquid medicine. To a certain extent, it can reduce the generation of air bubbles and improve the consistency of flow rate in each injection hole. Afterwards, the first valve core and the valve body remain in contact, and the liquid medicine in the transition chamber enters the outlet chamber and passes through the first gap and the first guide groove into the liquid flow channel, replenishing the distribution chamber and the injection hole connected to it, so as to achieve stable injection. The liquid medicine is ejected simultaneously through at least two injection holes on the needleless injection head, which can achieve a larger dose injection per unit time and higher injection efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an embodiment of the needle-free injector of this utility model; Figure 2 yes Figure 1 A cross-sectional view of the fluid-carrying body through the plane of symmetry; Figure 3 yes Figure 1 A sectional view through the plane of symmetry; Figure 4 yes Figure 3 A schematic diagram of the structure in the liquid extraction state; Figure 5 yes Figure 3 A schematic diagram of the injection state structure; Figure 6 yes Figure 3 A magnified structural diagram of part A; Figure 7 yes Figure 3 A schematic diagram of the enlarged structure of part B; Figure 8 This is a cross-sectional view of the first valve core through the plane of symmetry; Figure 9 This is a left view of the first valve core; Figure 10 This is a right view of the first valve core; Figure 11 This is a schematic diagram of an embodiment of a needle-free injection head; Figure 12 yes Figure 11 Left view of the corresponding needle-free injection head; Figure 13 This is a schematic diagram of another embodiment of the needle-free injection head; Figure 14 yes Figure 13 Left view of the corresponding needle-free injection head. Detailed Implementation

[0018] 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.

[0019] like Figures 1 to 10As shown, this utility model discloses an embodiment of a needleless injector, including a liquid-injecting body 1, a needleless injection head 2, and a liquid-dispensing valve 3. The liquid-injecting body 1 is provided with a liquid-dispensing chamber 11, a transition chamber 12, and a power chamber 13. The transition chamber 12 is used for pre-filling with medication, and the cross-sectional area of ​​the transition chamber 12 is smaller than the cross-sectional area of ​​the liquid-dispensing chamber 11. A first piston 4 is provided in the power chamber 13, and the first piston 4 is connected to a power source. The needleless injection head 2 is provided with a dispensing chamber 21 and at least two injection holes 22, and the injection holes 22 communicate the dispensing chamber 21 with the outside. The liquid-dispensing valve 3 includes a valve body 31 and a first valve core 32. The valve body 31 is connected to the liquid-injecting body 1 and the needleless injection head 2. At least one sealed connection is provided. The valve body 31 has an axially penetrating liquid passage 311 that is opposite to the distribution chamber 21. The outer peripheral surface of the first valve core 32 has a first gap a with the inner wall of the outlet chamber 11. The end of the first valve core 32 away from the transition chamber 12 is provided with a first liquid guide groove 321. The first liquid guide groove 321 is provided with an opening facing the valve body 31 and is connected to the liquid passage 311 and the first gap a. The first valve core 32 is located at the end of the outlet chamber 11 near the transition chamber 12. The first valve core 32 can move axially back and forth as the pressure of the liquid in the transition chamber 12 changes, so that the first gap a is connected to or disconnected from the transition chamber 12.

[0020] In this embodiment, the needleless injection head 2 is provided with a dispensing cavity 21 and at least two injection holes 22. The cross-sectional area of ​​the transition cavity 12 of the liquid-conducting body 1 is set to be smaller than the cross-sectional area of ​​the outlet cavity 11. The first valve core 32 is disposed in the outlet cavity 11, and the outer peripheral surface of the first valve core 32 has a first gap a with the inner wall of the outlet cavity 11. The end of the first valve core 32 away from the transition cavity 12 is provided with a first liquid guide groove 321 that opens toward the valve body 31. The first liquid guide groove 321 connects the first gap a with the liquid flow channel 311 on the valve body 31. The liquid flow channel 311 is opposite to the dispensing cavity 21 of the needleless injection head 2. The needleless injection head 2 is provided with at least two injection holes 22 that connect the dispensing cavity 21 with the outside. When the first piston 4 of the power cavity 13 is driven by the power source to compress the liquid in the transition cavity 12, the first valve core 32 moves axially at the end of the outlet cavity 11 near the transition cavity 12, specifically moving away from the transition cavity 12. When valve core 32 is not in contact with valve body 31, the liquid medicine in transition chamber 12 enters outlet chamber 11 and passes through first gap a. Part of it enters liquid flow channel 311 through first guide groove 321, and another part enters liquid flow channel 311 through the gap between first valve core 32 and first valve body 31. The liquid medicine entering the liquid flow channel has a larger flow rate and a relatively smaller flow velocity, which helps to fill distribution chamber 21 and each injection hole 22 with liquid medicine. To a certain extent, it can reduce the generation of air bubbles and improve the flow consistency of each injection hole 22. Afterwards, first valve core 32 and valve body 31 remain in contact, and liquid medicine in transition chamber 12 enters outlet chamber 11 and passes through first gap a and first guide groove 321 into liquid flow channel 311, replenishing distribution chamber 21 and the connected injection hole 22 to achieve stable injection. Liquid medicine is ejected simultaneously through at least two injection holes 22 on needleless injection head 2, which can achieve a larger dose injection per unit time and higher injection efficiency.

[0021] Specifically, in this embodiment, the valve body 31 is provided with a first abutment cavity 312, which is coaxially arranged with the liquid flow channel 311. A first elastic reset member 33 is provided within the first abutment cavity 312. The first valve core 32 is provided with a second abutment cavity 322 opposite to the first abutment cavity 312, and the first elastic reset member 33 abuts against the second abutment cavity 322. When the pressure of the liquid in the transition cavity 12 on the first valve core 32 is less than the elastic force of the first elastic reset member 33, the first valve core 32 will move towards the transition cavity 12 or remain in a state of blocking the transition cavity 12.

[0022] The first valve core 32 has a first protruding ring 323 and a second protruding ring 324 at its two ends, respectively. Both the first protruding ring 323 and the second protruding ring 324 protrude outwards from the outer peripheral surface of the first valve core 32 and are adapted to the liquid outlet chamber 11. The first protruding ring 323 and the second protruding ring 324 play a guiding role when the first valve core 32 moves axially, helping to improve the stability of the first valve core 32 moving axially, thereby making the injection flow more stable.

[0023] The first liquid guiding groove 321 axially penetrates the axial groove of the first convex ring 323 and the radial groove communicating with the second abutment cavity 322. The second convex ring 324 is provided with a second liquid guiding groove 325, which axially penetrates the second convex ring 324 and communicates with the first gap a, so that the liquid medicine in the transition cavity 12 can enter the first gap a.

[0024] The first liquid guiding groove 321 and the second liquid guiding groove 325 are preferably tangent to the outer peripheral surface of the first valve core 32 in order to reduce unnecessary disturbances during the flow of the liquid.

[0025] In this embodiment, the end face of the first valve core 32 opposite to the transition cavity 12 is provided with a sealing groove 326, and a first sealing element for sealing the transition cavity 12 is provided in the sealing groove 326. When the first sealing element abuts against the injection cavity, the first gap a is disconnected from the transition cavity 12. When the pressure of the liquid in the transition cavity 12 increases, driving the first valve core 32 away from the transition cavity 12, the first sealing element releases the seal on the transition cavity 12, and the first gap a communicates with the transition cavity 12. Since the cross-sectional area of ​​the transition cavity 12 is smaller than the cross-sectional area of ​​the liquid outlet 11, at the instant the transition cavity 12 communicates with the first gap a, the pressure acting on the surface of the first valve core 32 increases with the increase of the contact area with the liquid, helping to push the first valve core 32 to move quickly to abut against the valve body 31, thereby accelerating the injection speed of the liquid.

[0026] In this embodiment, the power chamber 13 of the liquid inlet body 1 is preferably coaxially arranged with the transition chamber 12 and the outlet chamber 11, so that the cross-sectional area of ​​the transition chamber 12 is smaller than that of the power chamber 13. During injection, the pre-filled liquid in the transition chamber 12 can more easily push the first valve core 32 to move at high speed, resulting in a greater initial velocity of the liquid and helping to increase the injection speed. The power chamber 13 is provided with a first piston 4, which reciprocates within the power chamber 13 to drive the liquid in the transition chamber 12 into the outlet chamber 11, or the liquid in the inlet channel 61 into the transition chamber 12.

[0027] In this embodiment, the dispensing chamber 21 of the needle-free injection head 2 specifically includes a central chamber 211 and radially arranged guide channels 212. The injection holes 22 are arranged in a circumferential array within the central chamber 211, and each injection hole 22 communicates with the central chamber 211 through a corresponding guide channel 212. In this embodiment, the liquid flow channel 311 is coaxially arranged with the central chamber 211. When the liquid in the liquid flow channel 311 collides with the central chamber 211, it will spray outwards evenly in a radial pattern, making the flow rate of each guide channel 212 more balanced and the flow rate uniformity of each injection hole 22 better. Figures 11 to 14 The structure of a needleless injection head 2 with 4 injection holes 22 and 6 injection holes 22 evenly distributed is given.

[0028] Of course, when the injection efficiency requirement is low, the needleless injection head of this embodiment can also be provided with only one injection hole. By replacing the needleless injection head 2 with different numbers of injection holes 22, such as 1 injection hole, 2 injection holes, 3 injection holes, 4 injection holes, 5 injection holes, and 6 injection holes, the injection efficiency can be adjusted.

[0029] The injection port 22 of the needleless injection head 2 specifically includes a first chamber 221, a second chamber 222, and a third chamber 223. The first chamber 221 communicates with the outside, the second chamber 222 connects the first chamber 221 and the third chamber 223, and the third chamber 223 communicates with the dispensing chamber 21. The cross-sectional areas of the first chamber 221 and the third chamber 223 are constant, which makes them easier to process and shape, and makes it easier to stabilize the injection effect. The cross-sectional area of ​​the first chamber 221 is smaller than that of the third chamber 223. The cross-sectional area of ​​the second chamber 222 gradually increases in the direction away from the first chamber 221, so that the flow cross-sectional area of ​​the liquid when flowing through the second chamber 222 becomes smaller, which promotes the increase of flow rate.

[0030] Meanwhile, in this embodiment, a positioning plane 23 corresponding to the injection hole 22 is provided at the front end of the needleless injection head 2. The first chamber 221 of the injection hole 22 is opened on the positioning plane 23, and the positioning planes 23 of each injection hole 22 are located on the same plane. The cross-sectional area of ​​the positioning plane 23 is close to the cross-sectional area of ​​the third chamber 223. During injection, the positioning plane 23 is directly in contact with the human skin, and no additional support cover is required, which further simplifies the assembly structure and reduces the cost of consumables.

[0031] The needleless injection head 2 also has an assembly cavity 24, which has a first plane 241. The dispensing cavity 21 is formed on the first plane 241, and the cross-section of the guide groove 212 is arc-shaped. The first plane 241 abuts against the end face of the valve body 31. A positioning boss is provided at the end of the valve body 31 that abuts against the first plane 241. The positioning boss abuts against the end face of the liquid-conducting body 1, and the other end extends into the liquid outlet cavity 11 of the liquid-conducting body 1. The valve body 31 is sealed to the circumferential sidewall of the assembly cavity 24 and to the circumferential sidewall of the liquid outlet cavity 11. The inner circumferential sidewall of the assembly cavity 24 of the needleless injection head 2 is provided with an internal thread. The assembly cavity 24 is threadedly connected to the end of the liquid-conducting body 1 where the liquid outlet cavity 11 is located, thereby realizing the positioning and assembly of the valve body 31.

[0032] In this embodiment, the power chamber 13, the transition chamber 12, the liquid outlet chamber 11, and the injection port 22 are coaxially arranged. The liquid inlet body 1 also has a liquid inlet chamber 14 that crosses and communicates with the transition chamber 12. The liquid inlet chamber 14 is used to inject liquid medicine into the transition chamber 12. The liquid inlet chamber 14 is provided with a liquid inlet valve 5 and a liquid inlet connector 6 connected thereto. The liquid inlet connector 6 has a liquid inlet channel 61 that communicates with the liquid inlet chamber 14. In this embodiment, the liquid inlet connector 6 is a Luer connector, which has a sealing ring that seals with the inner wall of the liquid inlet chamber 14.

[0033] The inlet valve 5 specifically includes a second valve core 51 and a second elastic reset member 52. In this embodiment, the first valve core 32 and the second valve core 51 preferably adopt the same structure, which is more convenient for assembly. Specifically, the outer peripheral surface of the second valve core 51 has a second gap b with the inner wall of the inlet cavity 14. The second gap b communicates with the transition cavity 12. The second valve core 51 has a third abutment cavity 511 on the side opposite to the inlet connector 6. The inlet cavity 14 has a fourth abutment cavity 141 that is opposite to the third abutment cavity 511. The second elastic reset member 52 abuts against the third abutment cavity 511 and the fourth abutment cavity 141, which can drive the second valve core 51 to move closer to the inlet channel 61 and disconnect the second gap b from the inlet channel 61. The second valve core 51 has a third protruding ring and a fourth protruding ring at its two ends respectively. The third protruding ring and the fourth protruding ring both protrude outward from the outer peripheral surface of the second valve core 51 and are adapted to the liquid inlet chamber 14. The second valve core 51 has a third liquid guide groove 512 at the end away from the transition chamber 12. The third liquid guide groove 512 axially penetrates the third protruding ring and communicates with the third abutment chamber 511 and the second gap b. The fourth protruding ring has a fourth liquid guide groove 513. The fourth liquid guide groove 513 axially penetrates the fourth protruding ring and communicates with the second gap b.

[0034] In this embodiment, both the first elastic reset member 33 and the second elastic reset member 52 are preferably compression springs.

[0035] In this embodiment, the inlet connector 6 is further provided with an inlet tube 7, and a second piston 8 is provided inside the inlet tube 7. The inlet tube 7, the second piston 8, and the inlet connector 6 constitute a conventional syringe. When the second piston 8 draws the liquid into the inlet tube 7, the second piston 8 seals the liquid in the inlet tube 7 by inserting the inlet tube 7 into the inlet chamber 14 of the liquid-conducting body 1. By pushing the second piston 8, pressure can be applied to the liquid in the inlet tube 7, and the second valve core 51 overcomes the pressure of the second elastic reset member 52 and moves away from the inlet connector 6. The second gap b communicates with the inlet channel 61, thereby realizing the pre-filling of the transition chamber 12 with liquid. In addition, the liquid in the inlet chamber channel 61 can also be drawn into the transition chamber 12 by pulling the first piston 4.

[0036] The operation of the needleless injector according to the embodiments of this utility model will be described below with reference to the accompanying drawings.

[0037] Liquid extraction status: such as Figure 4 As shown, the first piston 4 moves to the right, and a negative pressure is formed in the transition chamber 12. The first valve core 32 moves to the right under the suction force of the transition chamber 12 and the force of the first elastic reset member 33 until it is limited by the liquid-passing body 1. At the same time, the second valve core 51 moves downward under the action of negative pressure, overcoming the elastic force of the second elastic reset member 52. The liquid enters the transition chamber 12 through the second gap bb.

[0038] Injection status: such as Figure 5 As shown, the first piston 4 moves to the left, pushing the liquid medicine in the transition chamber 12 to gather to the left and creating a thrust on the first valve core 32. The first valve core 32 moves to the left until it is limited by the valve body 31. The liquid medicine flows into the liquid passage 311 of the valve body 31 through the second liquid guide groove 325, the first gap a, and the first liquid guide groove 321. It is then distributed to each injection hole 22 through the distribution chamber 21 of the needleless injection head 2 for injection. At the same time, under the hydraulic action in the transition chamber 12 and the elastic force of the second elastic reset member 52, the second valve core 51 moves upward until it is limited by the Luer joint. At this time, the liquid medicine cannot flow into the transition chamber 12 through the second gap b.

[0039] In this embodiment, the liquid inlet 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, the liquid inlet connector 6, 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.

[0040] 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 for fluid infusion, a needleless injection head, and an outlet valve. The liquid-conducting body is provided with a liquid outlet chamber, a transition chamber and a power chamber. The transition chamber is used for pre-filling with liquid medicine. The cross-sectional area of ​​the transition chamber is smaller than that of the liquid outlet chamber. The power chamber is provided with a first piston, which is connected to a power source. The needleless injection head has a dispensing cavity and at least two injection holes, the injection holes being connected to the dispensing cavity and the outside. The dispensing valve includes a valve body and a first valve core. The valve body is sealed to at least one of the liquid-passing body and the needle-free injection head. The valve body has an axially penetrating liquid passage opposite to the dispensing chamber. The outer peripheral surface of the first valve core has a first gap with the inner wall of the dispensing chamber. The end of the first valve core away from the transition chamber has a first liquid guide groove. The first liquid guide groove is disposed facing the opening of the valve body and is connected to the liquid passage and the first gap. The first valve core is disposed at the end of the dispensing chamber near the transition chamber. The first valve core can move axially back and forth as the pressure of the liquid in the transition chamber changes, so that the first gap communicates with or disconnects from the transition chamber.

2. The needleless injector according to claim 1, characterized in that, The valve body is provided with a first abutting cavity, which is coaxially arranged with the liquid flow channel. A first elastic reset member is provided in the first abutting cavity. The first valve core is provided with a second abutting cavity opposite to the first abutting cavity. The first elastic reset member abuts against the second abutting cavity.

3. The needleless injector according to claim 2, characterized in that, The first valve core has a first convex ring and a second convex ring at its two ends respectively. The first convex ring and the second convex ring both protrude outward from the outer peripheral surface of the first valve core and are adapted to the liquid outlet cavity. The first liquid guide groove axially penetrates the first convex ring and communicates with the second abutment cavity. The second convex ring has a second liquid guide groove axially penetrates the second convex ring and communicates with the first gap.

4. The needleless injector according to claim 1, characterized in that, The end face of the first valve core opposite to the transition cavity is provided with a sealing groove, and a first sealing element for sealing the transition cavity is provided in the sealing groove.

5. The needleless injector according to claim 1, characterized in that, The dispensing chamber includes a central cavity and radially arranged guide channels from the central cavity. The injection holes are arranged in a circumferential array in the central cavity and communicate with the central cavity through the corresponding guide channels. The liquid flow channel is coaxially arranged with the central cavity.

6. The needleless injector according to claim 5, characterized in that, The needleless injection head is further provided with an assembly cavity, and the assembly cavity is provided with a first plane. The dispensing cavity is opened on the first plane, and the cross-section of the guide groove is arc-shaped. The first plane abuts against the end face of the valve body, and the valve body is sealed with the assembly cavity.

7. The needleless injector according to claim 1, characterized in that, The injection port includes a first chamber, a second chamber, and a third chamber. The first chamber communicates with the outside. The second chamber connects the first chamber and the third chamber. The third chamber communicates with the dispensing chamber. The cross-sectional areas of the first chamber and the third chamber are constant, and the cross-sectional area of ​​the first chamber is smaller than that of the third chamber. The cross-sectional area of ​​the second chamber gradually increases in the direction away from the first chamber.

8. The needleless injector according to claim 1, characterized in that, It also includes an inlet valve and an inlet connector. The liquid-conducting 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 valve includes a second valve core and a second elastic reset member. The outer peripheral surface of the second valve core has a second gap with the inner wall of the inlet chamber. The second gap communicates with the transition chamber. The side of the second valve core facing away from the inlet connector is provided with a third abutment cavity. The inlet chamber is provided with a fourth abutment cavity that is opposite to the third abutment cavity. The second elastic reset member abuts against the third abutment cavity and the fourth abutment cavity, which can drive the second valve core to move towards the inlet channel and disconnect the second gap from the inlet channel.

9. The needleless injector according to claim 8, characterized in that, The second valve core has a third protruding ring and a fourth protruding ring at its two ends, respectively. Both the third and fourth protruding rings protrude outwards from the outer circumferential surface of the second valve core and are adapted to the liquid inlet chamber. The second valve core has a third liquid guide groove at the end away from the transition chamber. The third liquid guide groove axially penetrates the third protruding ring and communicates with the third abutment chamber and the second gap. The fourth protruding ring has a fourth liquid guide groove axially penetrates the fourth protruding ring and communicates with the second gap.

10. The needleless injector according to claim 8, characterized in that, The power chamber, the transition chamber, and the outlet chamber are coaxially arranged. The cross-sectional area of ​​the transition chamber is smaller than that of the power chamber. The first piston reciprocates within the power chamber to drive the liquid medicine in the transition chamber into the outlet chamber, or the liquid medicine in the inlet channel into the transition chamber.

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