Needleless injector

Abstract

This utility model discloses a needle-free injector, relating to the field of medical device technology. The needle-free injector includes: a main body with a first cavity and a second cavity connected by a connecting tube; the first cavity includes a first channel and a second channel; the first channel is connected to the connecting tube; an injection head is provided on the second channel; a piston movably disposed in the second cavity; an injection tube connected to the main body, the injection chamber of the injection tube being connected to the connecting tube; a Luer connector connected to the injection chamber, with an injection needle connected to the Luer connector; a first valve body movably disposed in the first cavity; and a second valve body movably disposed within the Luer connector. By configuring both the first and second valve bodies as radially sealing movable parts, the sealing surface remains in contact under spring preload during valve body displacement, and the gap is automatically compensated after valve body wear, effectively improving the sealing stability of the injector.

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. They are medical devices that inject liquid medications into the patient's skin, subcutaneous tissue, or muscle through a micro-hole at the tip, thus sparing the patient the pain of needle pricks.

[0003] However, current needle-free injectors still have some technical shortcomings, including insufficient reliability of fluid circuit control: most needle-free injectors are designed with a single valve structure, which can easily lead to air mixing into the liquid due to poor sealing during the negative pressure aspiration phase; during positive pressure injection, the valve response delay will cause pressure loss and affect the liquid injection depth. Dynamic sealing stability is also poor: the valve body and cavity use a planar fit seal, and after long-term use, wear and tear will increase the leakage rate, shortening the equipment's lifespan. Utility Model Content

[0004] To address the shortcomings of existing technologies, this invention provides a needle-free injector that can effectively improve dynamic sealing performance and reduce the risk of leakage.

[0005] To address the aforementioned technical problems, this utility model provides a needle-free injector in a first aspect, comprising: a main body having a first cavity and a second cavity connected by a connecting tube; the first cavity including a first channel and a second channel; the first channel communicating with the connecting tube; an injection head disposed on the second channel; a piston movably disposed in the second cavity; and a first valve body movably disposed in the first cavity; the first valve body having a first guide cavity connected to the connecting tube, and a first connecting hole communicating with the first guide cavity being formed on the side wall of the first valve body; wherein, in a normal state, the first valve body closes the first connecting hole through the first channel, and when the first connecting hole slides into the second channel, the first connecting hole is exposed to the second channel. The system comprises: an injection head; an injection tube connected to the main body, the injection chamber of which is connected to the connecting tube; a Luer connector, the first end of which extends into the injection chamber and has an infusion chamber, the second end of which has an inlet chamber, the infusion chamber including a third channel and a fourth channel; the third channel communicating with the inlet chamber; and the fourth channel communicating with the injection chamber; a second valve body movably disposed in the infusion chamber; the second valve body having a third guide chamber communicating with the inlet chamber, and a first connecting hole communicating with the third guide chamber on the side wall of the second valve body; wherein, in the normal state, the first valve body closes the third connecting hole through the third channel, and when the third connecting hole slides into the second channel, the third connecting hole is exposed to the fourth channel and communicates with the connecting tube.

[0006] As an improvement to the above solution, the first valve body includes a first movable part and a second movable part coaxially connected; the outer wall of the first movable part is sealed against the first channel, and a first gap is formed between the second movable part and the inner wall of the second channel; the second movable part is connected to the injection head through a first spring; the first movable part is provided with a first guide cavity and a first connecting hole on the side wall of the first movable part; the second movable part is provided with a second guide cavity communicating with the injection head, and a second connecting hole communicating with the second guide cavity and the first gap is opened on the side wall of the second movable part; wherein, when the first spring is compressed, the first movable part slides into the second channel, exposing the first connecting hole to the first gap.

[0007] As an improvement to the above solution, the second valve body includes a third movable part and a fourth movable part coaxially connected. The outer wall of the third movable part is sealed against the third channel, and a second gap is formed between the fourth movable part and the inner wall of the fourth infusion channel. The fourth movable part is connected to the inner wall of the infusion chamber by a second spring. The third movable part is provided with a third guide cavity, and the side wall of the third movable part is provided with a third connecting hole. The fourth movable part is provided with a fourth guide cavity communicating with the injection chamber, and the side wall of the fourth movable part is provided with a fourth connecting hole communicating with the fourth guide cavity and the second gap. When the second spring is compressed, the third movable part slides into the fourth infusion channel, exposing the third connecting hole to the second gap.

[0008] As an improvement to the above solution, a first sealing groove is provided at the connection between the first movable part and the second movable part, and a first sealing ring is provided in the first sealing groove. The first sealing ring is used to seal the first channel.

[0009] As an improvement to the above solution, a second sealing groove is provided at the connection between the third movable part and the fourth movable part, and a second sealing ring is provided in the second sealing groove. The second sealing ring is used to seal the third channel.

[0010] As an improvement to the above solution, the second cavity includes a first driving channel and a second driving channel that are connected, wherein the inner diameter of the first driving channel is smaller than that of the second driving channel.

[0011] As an improvement to the above solution, the piston includes a push rod portion and a connecting portion. The push rod portion is slidably sealed in the first drive channel, and the connecting portion is slidably disposed in the second drive channel. The connecting portion is used to connect to an external booster device.

[0012] As an improvement to the above solution, the inlet chamber at the second end of the Luer connector is connected to the injection needle tube.

[0013] As an improvement to the above solution, at least three first connecting holes are provided, and multiple first connecting holes are evenly arranged around the circumference of the first movable part; at least three second connecting holes are provided, and multiple second connecting holes are evenly arranged around the circumference of the second movable part; at least three third connecting holes are provided, and multiple third connecting holes are evenly arranged around the circumference of the third movable part.

[0014] As an improvement to the above solution, the injection head is provided with a first limiting groove on the side near the first cavity, and the first limiting groove is connected to the injection cavity of the injection head; one end of the first spring is connected to the first limiting groove, and the other end of the first spring is connected to the second guide cavity.

[0015] As an improvement to the above solution, a second limiting groove is provided on the side of the injection chamber near the connecting pipe, and the second limiting groove is connected to the connecting pipe; one end of the second spring is connected to the second limiting groove, and the other end of the second spring abuts against the fourth guide cavity.

[0016] As an improvement to the above scheme, the angle between the injection tube and the main tube is 30° to 90°.

[0017] The beneficial effects of implementing this utility model are as follows:

[0018] This invention discloses a needle-free injector. By configuring both the first and second valve bodies as radially sealed movable parts, the sealing surface remains in contact under spring preload during valve body displacement. The valve body automatically compensates for gaps after wear, effectively improving the injector's lifespan and sealing stability. Furthermore, by incorporating a variable-diameter infusion chamber within the Luer connector, it simultaneously performs interface connection, fluid path control, and valve body containment functions, reducing external connection points and mitigating leakage risks. Both the first and second valve bodies employ mechanical linkage response, eliminating the need for electronic control and enabling precise timing actions, thus reducing the failure rate. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the structure of a needle-free injector according to an embodiment of this application;

[0020] Figure 2 This is an exploded view of the structure of a needle-free injector according to an embodiment of this application;

[0021] Figure 3 This is a cross-sectional view of the main body and injection tube of a needleless injector according to an embodiment of this application;

[0022] Figure 4 This is a partial structural schematic diagram of a needle-free injector according to an embodiment of this application;

[0023] Figure 5This is a schematic diagram of the structure of a Luer connector for a needleless injector according to an embodiment of this application;

[0024] Figure 6 This is an embodiment of the present application. Figure 1 A magnified view of a section at point A in the middle;

[0025] Figure 7 This is a schematic diagram of liquid aspiration using a needleless injector as described in an embodiment of this application;

[0026] Figure 8 This is a schematic diagram of liquid injection using a needleless injector as described in an embodiment of this application.

[0027] The reference numerals in the attached drawings are explained as follows: 100, main body; 110, first cavity; 111, first channel; 112, second channel; 1121, first gap; 120, second cavity; 121, first drive channel; 122, second drive channel; 130, connecting pipe; 200, piston; 210, push rod part; 220, connecting part; 300, injection pipe; 310, injection chamber; 311, second limiting groove; 400, Luer connector; 410, infusion chamber; 411, third channel; 412, fourth channel; 4121, second gap; 420, inlet chamber; 500, first valve body; 510, first movable part; 511, first guide chamber; 512, first connecting hole; 520, second movable part; 521, first... 522. Second guide cavity; 530. First spring; 600. Second valve body; 610. Third movable part; 611. Third guide cavity; 612. Third connecting hole; 620. Fourth movable part; 621. Fourth guide cavity; 622. Fourth connecting hole; 630. Second spring; 700. Injection head; 710. First limiting groove; 800. Injection needle tube; 901. First sealing ring; 902. Second sealing ring; 903. Third sealing ring; 904. Fourth sealing ring; 905. Fifth sealing ring; 9051. Sealing gasket; 906. Sixth sealing ring; 907. Seventh sealing ring; 908. Eighth sealing ring; 909. Ninth sealing ring; 910. Tenth sealing ring; 911. Eleventh sealing ring. Detailed Implementation

[0028] 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.

[0029] See Figures 1-3 , Figure 1 This is a cross-sectional view of the structure of a needle-free injector according to an embodiment of this application; Figure 2 This is an exploded view of the structure of a needle-free injector according to an embodiment of this application; Figure 3This is a cross-sectional view of the main body and injection tube of a needle-free injector according to an embodiment of this application. As shown in the figure, the needle-free injector includes: a main body 100, which has a first cavity 110 and a second cavity 120 connected by a connecting tube 130; the first cavity 110 includes a first channel 111 and a second channel 112; the first channel 111 is connected to the connecting tube 130; an injection head 700 is provided on the second channel 112; a piston 200 is movably disposed in the second cavity 120; an injection tube 300 is connected to the main body 100, and the injection chamber 310 of the injection tube 300 is connected to the connecting tube 130; a Luer connector 400 is connected to the injection chamber 310, and an injection needle is connected to the Luer connector 400; a first valve body 500 is movably disposed in the first cavity 110; and a second valve body 600 is movably disposed in the Luer connector 400.

[0030] See Figure 1 and Figure 4 , Figure 4 This is a partial structural schematic diagram of a needle-free injector according to an embodiment of this application;

[0031] Furthermore, in this embodiment, the first valve body 500 includes a first movable part 510 and a second movable part 520 coaxially connected; the outer wall of the first movable part 510 is sealed against the first channel 111, and a first gap 1121 is formed between the second movable part 520 and the inner wall of the second channel 112; the second movable part 520 is connected to the injection head 700 via a first spring 530; the first movable part 510 has a first guide cavity 511 that engages with the connecting tube 130, and the side wall of the first movable part 510 has a first connecting hole 512 that connects to the first guide cavity 511; the second movable part 520 has a second guide cavity that connects to the injection head 700. The guide cavity 521 has a second connecting hole 522 on its side wall, which connects the second guide cavity 521 and the first gap 1121. In the normal state, the first movable part 510 closes the first connecting hole 512 through the first channel 111. When the first spring 530 is compressed, the first movable part 510 slides into the second channel 112, exposing the first connecting hole 512 to the first gap 1121. At this time, the liquid medicine in the injection head 700 enters the second cavity 120 in sequence through the inlet cavity 420, the third guide cavity 611, the third connecting hole 612, the second gap 4121, the fourth connecting hole 622, the fourth guide cavity 621, and the connecting tube 130.

[0032] By setting the first valve body 500 to a radial sealing method for the movable part, the sealing surface is always kept in contact by the spring preload during the valve body displacement process. After the valve body wears, the gap is automatically compensated, which can effectively improve the life cycle and sealing stability of the syringe. A three-stage pressurization channel is formed through the first connecting hole 512, the first gap 1121 and the second connecting hole 522 to increase the jet velocity and improve the skin penetration efficiency.

[0033] See Figure 2 and Figure 4 Furthermore, in this embodiment, a first sealing groove is provided at the connection between the first movable part 510 and the second movable part 520, and a first sealing ring 901 is provided in the first sealing groove. The first sealing ring 901 is used to seal the first channel 111, further improving the airtightness of the first valve body 500.

[0034] Preferably, the cross-sectional radius of the second movable part 520 is larger than that of the first movable part 510, which can assist the first sealing ring 901 in sealing.

[0035] See Figure 1 and Figure 5 , Figure 5 This is a schematic diagram of the structure of a Luer connector 400 of a needleless injector according to an embodiment of this application;

[0036] Furthermore, in this embodiment, the first end of the Luer connector 400 extends into the injection chamber 310 and is provided with an infusion chamber 410. The second end of the Luer connector 400 is provided with an inlet chamber 420. The infusion chamber 410 includes a third channel 411 and a fourth channel 412 that communicate with each other. The third channel 411 communicates with the inlet chamber 420. The fourth channel 412 communicates with the injection chamber 310. The injection chamber 310 is connected to the injection needle tube 800 via Luer threads. By providing a variable-diameter infusion chamber 410 inside the Luer connector 400, it simultaneously undertakes the triple functions of interface connection, fluid circuit control, and valve body accommodation, reducing external connection points and lowering the risk of leakage.

[0037] See Figure 1 and Figure 6 , Figure 6 This is an embodiment of the present application. Figure 1 A magnified view of a portion of point A in the middle.

[0038] Furthermore, in this embodiment, the second valve body 600 includes a third movable part 610 and a fourth movable part 620 coaxially connected. The outer wall of the third movable part 610 is in sealing contact with the third channel 411, and a second gap 4121 is formed between the fourth movable part 620 and the inner wall of the fourth infusion channel. The fourth movable part 620 is connected to the inner wall of the infusion chamber 410 via a second spring 630. The third movable part 610 is provided with a third guide cavity 611 communicating with the infusion chamber 420, and the side wall of the third movable part 610 is provided with a third connecting hole 612 communicating with the third guide cavity 611. The fourth movable part 620 is provided with a connecting hole 612 communicating with the infusion chamber 420. The fourth guide cavity 621 of the liquid cavity 310 has a fourth connecting hole 622 on the side wall of the fourth movable part 620, which connects the fourth guide cavity 621 and the second gap 4121. In the normal state, the third movable part 610 closes the third connecting hole 612 through the third channel 411. When the second spring 630 is compressed, the third movable part 610 slides into the fourth infusion channel, exposing the third connecting hole 612 to the second gap 4121. At this time, the liquid medicine in the second cavity 120 enters the injection head 700 in sequence through the first guide cavity 511, the first connecting hole 512, the first gap 1121, the second connecting hole 522, and the second guide cavity 521.

[0039] By setting the second valve body 600 to a radial sealing method for the moving part, the sealing surface is always kept in contact by the spring preload during the valve body displacement process. After the valve body wears, the gap is automatically compensated, which can effectively improve the life cycle and sealing stability of the syringe.

[0040] See Figure 2 and Figure 6 Furthermore, in this embodiment, a second sealing groove is provided at the connection between the third movable part 610 and the fourth movable part 620, and a second sealing ring 902 is provided in the second sealing groove. The second sealing ring 902 is used to seal the third channel 411, thereby further improving the airtightness of the second valve body 600.

[0041] Preferably, the cross-sectional radius of the fourth movable part 620 is greater than the cross-sectional radius of the third movable part 610.

[0042] See Figure 3 Furthermore, in this embodiment, the second cavity 120 includes a first driving channel 121 and a second driving channel 122 that are connected. The inner diameter of the first driving channel 121 is smaller than that of the second driving channel 122. This design can improve the driving force in the inner area of ​​the second cavity 120 during liquid injection, increase the liquid flow rate, and prevent the liquid from sticking together.

[0043] See Figure 1 and Figure 2Furthermore, in this embodiment, the piston 200 includes a push rod portion 210 and a connecting portion 220. The push rod portion 210 is slidably sealed to the first drive channel 121, and the connecting portion 220 is slidably disposed in the second drive channel 122. The connecting portion 220 is used to connect to an external booster device.

[0044] See Figure 1 and Figure 2 Preferably, the connecting part 220 is provided with at least one third sealing groove, and the third sealing groove is provided with a third sealing ring 903, which abuts against the inner wall of the second driving channel 122; the push rod part 210 is provided with a fourth sealing groove and a fifth sealing groove, the fourth sealing groove is provided with a fourth sealing ring 904, and the fifth sealing groove is provided with a sealing gasket 9051 and a fifth sealing ring 905, both of which abut against the inner wall of the first driving channel 121, so as to improve the airtightness of the piston 200 and ensure that the liquid medicine flows in the specified direction.

[0045] See Figure 2 and Figure 4 Preferably, a sixth sealing ring 906 is provided at the connection between the injection head 700 and the opening of the second channel 112; a seventh sealing ring 907 is provided on the outer wall of the first movable part 510 near the connecting pipe; and an eighth sealing ring 908 is provided on the outer wall of the second movable part 520 near the injection head 700, so as to improve the airtightness of the first cavity 110.

[0046] See Figure 2 and Figure 6 Preferably, a ninth sealing ring 909 is provided at the connection between the Luer connector 400 and the opening of the injection chamber 310; a tenth sealing ring 910 is provided on the side of the third movable part 610 near the inlet chamber 420; and an eleventh sealing ring 911 is provided on the side of the fourth movable part 620 near the connecting pipe 130, so as to improve the airtightness of the injection pipe 300 and ensure that the liquid flows in the specified direction.

[0047] Preferably, at least three first connecting holes 512 are provided, and the plurality of first connecting holes 512 are evenly arranged along the circumference of the first movable part 510; at least three second connecting holes 522 are provided, and the plurality of second connecting holes 522 are evenly arranged along the circumference of the second movable part 520; at least three third connecting holes 612 are provided, and the plurality of third connecting holes 612 are evenly arranged along the circumference of the third movable part 610.

[0048] See Figure 4Furthermore, in this embodiment, the injection head 700 is provided with a first limiting groove 710 on the side near the first cavity 110. The first limiting groove 710 communicates with the injection cavity of the injection head 700 and is coaxially arranged. One end of the first spring 530 is connected to the first limiting groove 710, and the other end of the first spring 530 is connected to the second guide cavity 521. The extension and retraction direction of the spring is limited by the first limiting groove 710.

[0049] See Figure 3 and Figure 6 Furthermore, in this embodiment, the injection cavity 310 is provided with a second limiting groove 311 on the side near the connecting pipe 130, and the second limiting groove 311 is connected to the connecting pipe 130; one end of the second spring 630 is connected to the second limiting groove 311, and the other end of the second spring 630 abuts against the fourth guide cavity 621.

[0050] Preferably, the angle between the injection tube 300 and the main tube 100 is 30° to 90°; more preferably 45°; the axial center lines of the first valve body 500 and the second valve body 600 are arranged in a non-parallel manner.

[0051] Preferably, the preload of the first spring 530 and the second spring 630 can be adjusted according to the viscosity of the medicine solution.

[0052] As can be seen from the above, the needle-free injector of this utility model, by setting both the first valve body 500 and the second valve body 600 as radially sealed movable parts, ensures that the sealing surface remains in contact under the spring preload during valve body displacement, and automatically compensates for gaps after valve body wear, effectively improving the lifespan and sealing stability of the injector; by setting a variable diameter infusion chamber 410 inside the Luer connector 400, it simultaneously undertakes the triple functions of interface connection, liquid circuit control, and valve body containment, reducing external connection points and lowering the risk of leakage; both the first valve body 500 and the second valve body 600 adopt mechanical linkage response, eliminating the need for electronic control, enabling precise timing actions and reducing the failure rate.

[0053] See Figure 7 , Figure 7 This is a schematic diagram of liquid aspiration using a needleless injector as described in an embodiment of this application.

[0054] This embodiment provides a liquid aspiration method using a needle-free injector in a second aspect, comprising the following steps:

[0055] Connect the injection syringe 800 to the Luer connector 400;

[0056] The drive piston 200 moves away from the first chamber 110, creating a negative pressure in the second chamber 120;

[0057] The first valve body 500 remains stationary under negative pressure, and the first connecting hole 512 on the first valve body 500 is in a closed state.

[0058] Specifically, in this state, the inner wall of the first channel 111 seals the first connecting hole 512, the first sealing ring 901 seals the first channel 111, and the first valve body 500 remains closed under the action of negative pressure and the spring force of the first spring 530.

[0059] The second valve body 600 is driven by negative pressure to compress the second spring 630, causing the third movable part 610 to slide into the fourth infusion channel; the third connecting hole 612 is exposed to the second gap 4121; the liquid in the injection needle tube 800 enters the second cavity 120 in sequence through the inlet cavity 420, the third guide cavity 611, the third connecting hole 612, the second gap 4121, the fourth connecting hole 622, the fourth guide cavity 621 and the connecting tube 130, thus completing the liquid aspiration.

[0060] As can be seen from the above, the liquid aspiration method of the needleless injector in this utility model ensures that the liquid is completely drawn in unidirectionally from the inlet chamber 420 by forcibly sealing the first valve body 500 through a negative pressure stage, thereby reducing the air mixing ratio in the liquid. The third connecting hole 612 of the second valve body 600 adopts an exposed opening, which can increase the aspiration flow rate of the liquid and prevent sticking.

[0061] See Figure 8 , Figure 8 This is a schematic diagram of liquid injection using a needleless injector as described in an embodiment of this application.

[0062] This utility model provides a method for injecting liquid using a needle-free injector in a third aspect, comprising the following steps:

[0063] The drive piston 200 moves toward the first chamber 110, pushing the liquid medicine in the second chamber 120 into the connecting pipe 130;

[0064] Part of the liquid enters the injection chamber 310, pushing the second valve body 600 to reset and sealing the second connection hole 522;

[0065] Specifically, in this state, the inner wall of the third channel 411 seals the third connecting hole 612, the second sealing ring 902 seals the third channel 411, and the second valve body 600 remains closed under the action of hydraulic pressure and the spring force of the second spring 630.

[0066] The remaining medication enters the first infusion channel, pushing the first valve body 500 to compress the first spring 530; causing the first movable part 510 to slide into the second infusion channel, exposing the first connecting hole 512 to the first gap 1121; the medication sequentially passes through the first guide cavity 511, the first connecting hole 512, the first gap 1121, the second connecting hole 522, and the second guide cavity 521 into the injection head 700, and is then ejected through the injection head 700 to complete the injection.

[0067] As can be seen from the above, in the injection method of the needleless injector of this utility model, when the piston 200 is pushed forward, the liquid first closes the second valve body 600 to form a hydraulic lock, blocking the backflow path; so that the hydraulic energy is concentrated on the first valve body 500, and forms a three-stage pressurization channel through the first connecting hole 512, the first gap 1121 and the second connecting hole 522, thereby increasing the jet speed and improving the skin penetration efficiency.

[0068] The above description is the preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications are also considered to be within the protection scope of this utility model.

Claims

1. A needle-free injector, characterized in that, include: The main body has a first cavity and a second cavity connected by a connecting pipe; the first cavity includes a first channel and a second channel connected by a connecting pipe. The first channel is connected to the connecting tube; the second channel is equipped with an injection head; The piston is movably disposed in the second chamber; A first valve body is movably disposed in a first cavity; the first valve body is provided with a first guide cavity for connecting the connecting pipe, and the side wall of the first valve body is provided with a first connecting hole for connecting the first guide cavity. In this configuration, the first valve body, under normal conditions, closes the first connection hole through the first channel. When the first connection hole slides into the second channel, the first connection hole is exposed to the second channel and communicates with the injection head. The injection tube is connected to the main body, and the injection chamber of the injection tube is connected to the connecting tube; A Luer connector has a first end that extends into the injection chamber and is provided with an infusion chamber, and a second end of the Luer connector is provided with an inlet chamber. The infusion chamber includes a third channel and a fourth channel that are connected. The third channel is connected to the inlet chamber, and the fourth channel is connected to the injection chamber. The second valve body is movably disposed in the infusion chamber; the second valve body is provided with a third guide chamber that communicates with the infusion chamber, and the side wall of the second valve body is provided with a first connecting hole that communicates with the third guide chamber; In this configuration, the first valve body normally closes the third connection hole through the third channel. When the third connection hole slides into the second channel, it exposes the third connection hole to the fourth channel and connects with the connecting pipe.

2. The needle-free injector according to claim 1, characterized in that, The first valve body includes a first movable part and a second movable part coaxially connected; the outer wall of the first movable part is sealed against the first channel, and a first gap is formed between the second movable part and the inner wall of the second channel; the second movable part is connected to the injection head through a first spring; the first movable part is provided with a first guide cavity and a first connecting hole on the side wall of the first movable part; the second movable part is provided with a second guide cavity communicating with the injection head, and a second connecting hole communicating with the second guide cavity and the first gap is opened on the side wall of the second movable part; When the first spring is compressed, the first movable part slides into the second channel, exposing the first connecting hole to the first gap.

3. A needle-free injector according to claim 2, characterized in that, The second valve body includes a third movable part and a fourth movable part coaxially connected. The outer wall of the third movable part is in sealing contact with the third channel, and a second gap is formed between the fourth movable part and the inner wall of the fourth infusion channel. The fourth movable part is connected to the inner wall of the infusion chamber by a second spring. The third movable part is provided with a third guide cavity and a third connecting hole on its side wall. The fourth movable part is provided with a fourth guide cavity communicating with the injection chamber, and a fourth connecting hole communicating with the fourth guide cavity and the second gap is opened on its side wall. When the second spring is compressed, the third movable part slides into the fourth infusion channel, exposing the third connecting hole to the second gap.

4. A needle-free injector according to claim 3, characterized in that, A first sealing groove is provided at the connection between the first movable part and the second movable part, and a first sealing ring is provided in the first sealing groove. The first sealing ring is used to seal the first channel. A second sealing groove is provided at the connection between the third movable part and the fourth movable part, and a second sealing ring is provided in the second sealing groove. The second sealing ring is used to seal the third channel.

5. A needle-free injector according to claim 1, characterized in that, The second cavity includes a first driving channel and a second driving channel that are connected, wherein the inner diameter of the first driving channel is smaller than that of the second driving channel. The piston includes a push rod portion and a connecting portion. The push rod portion is slidably sealed in the first drive channel, and the connecting portion is slidably disposed in the second drive channel. The connecting part is used to connect to an external booster device.

6. A needle-free injector according to claim 1, characterized in that, The inlet chamber at the second end of the Luer connector is connected to the injection needle tube.

7. A needle-free injector according to claim 1, characterized in that, The first connecting hole is provided with at least three, and the plurality of the first connecting holes are evenly arranged along the circumference of the first movable part; The second connecting hole is provided with at least three, and the plurality of the second connecting holes are evenly arranged along the circumference of the second movable part; The third connecting hole is provided with at least three, and the plurality of the third connecting holes are evenly arranged along the circumference of the third movable part.

8. A needle-free injector according to claim 1, characterized in that, The injection head is provided with a first limiting groove on the side near the first cavity, and the first limiting groove is connected to the injection cavity of the injection head; one end of the first spring is connected to the first limiting groove, and the other end of the first spring is connected to the second guide cavity.

9. A needle-free injector according to claim 1, characterized in that, The injection chamber is provided with a second limiting groove on the side near the connecting pipe, and the second limiting groove is connected to the connecting pipe; one end of the second spring is connected to the second limiting groove, and the other end of the second spring abuts against the fourth guide cavity.

10. A needle-free injector according to claim 1, characterized in that, The angle between the injection tube and the main tube is 30° to 90°.

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