A needleless syringe

Abstract

The present invention relates to the technical field of syringes, and in particular to a needleless syringe, comprising: a housing; a barrel assembly; a piston, on which a push rod for pushing the liquid medicine in the barrel assembly is drivingly connected; an energy storage chamber, which is communicated with a gas supply chamber; a control chamber, which is communicated with the gas supply chamber; a balance valve, with the energy storage chamber and the control chamber respectively located on both sides of the valve core; and a control valve. The present invention utilizes the compressed air in the gas supply chamber to enter the energy storage chamber and the control chamber simultaneously. As the compressed air continuously enters the energy storage chamber, the pressure of the compressed air in the energy storage chamber gradually increases, and the pressure of the compressed air in the control chamber also increases synchronously to balance the thrust of the compressed air in the energy storage chamber that causes the valve core to disengage from the cylinder barrel, so as to meet the firing pressure required by the piston, thereby realizing high-pressure firing under the action of low-pressure compressed air, greatly reducing the use cost, having a high safety factor and good market prospects.

Description

Technical Field

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

[0002] With the development of technology, China has become one of the few countries in the world that can produce needleless syringes. It mainly uses the principle of high-pressure jet to make the liquid medicine form a finer liquid flow to instantaneously penetrate the skin and reach the subcutaneous tissue, with the advantages of uniform diffusion of the liquid medicine, fast onset time, high drug absorption rate, and small wound;

[0003] In order to prevent swine fever, pigs need to be vaccinated multiple times during the growth cycle. The traditional injection method is to use a needle syringe for injection. However, there are many pigs in the farm, and it is impossible to replace the needle for each pig. Therefore, usually, one needle is used to inject multiple pigs. However, once a pig has a problem, it is easy to cause a large-scale swine fever in the farm;

[0004] In response to this, more and more breeding enterprises have begun to use needleless syringes to inject vaccines. Since the epidermis of pigs is thick, a relatively high pressure is required for the liquid medicine to penetrate the epidermis. Existing needleless syringes generally enlarge the specifications of the needleless syringe used for humans and use high-pressure gases such as carbon dioxide gas for air supply. However, in order to prevent viruses from entering the breeding factory, the current breeding factory has very strict control over the entry and exit of personnel, which makes it very troublesome to replace the carbon dioxide gas cylinder. If compressed air is used as the gas source, this problem can be solved and the use cost can be reduced. However, the pressure of the compressed air generated by ordinary compressors is usually lower than 1 MPa, and although the compressed air generated by high-pressure compressors can meet the injection requirements of existing needleless syringes, it also brings the problem of high cost. In addition, using high-pressure compressed air has certain safety hazards;

[0005] In view of this, the present invention aims to provide a needleless syringe that can perform high-pressure injection under the action of low-pressure compressed air. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: in order to solve the problem that the existing needleless syringe needs to use high-pressure compressed air to achieve high-pressure firing of the liquid medicine, a needleless syringe is provided, which can achieve high-pressure firing of the liquid medicine under the action of low-pressure compressed air.

[0007] The technical solution adopted by the present invention to solve its technical problems is: a needleless syringe, comprising:

[0008] A housing having an inner cavity and an air supply cavity, and a cylinder is provided in the inner cavity;

[0009] A barrel assembly for placing the liquid medicine;

[0010] A piston is slidably installed inside a cylinder barrel, and a push rod for pushing the liquid medicine in the barrel assembly is drivingly connected to the piston;

[0011] An energy storage cavity is communicated with the air supply cavity;

[0012] A control cavity is communicated with the air supply cavity;

[0013] A balance valve has a valve core and a first elastic element for pressing the valve core against the end of the cylinder barrel. The energy storage cavity and the control cavity are respectively located on both sides of the valve core;

[0014] And a control valve is arranged on the connecting flow path between the control cavity and the air supply cavity. The control valve has a first state and a second state. In the first state, the connecting flow path is communicated, and the control valve allows the gas in the air supply cavity to enter the control cavity, and the valve core remains pressed against the end of the cylinder barrel; in the second state, the connecting flow path is cut off, the control valve blocks the gas in the air supply cavity from entering the control cavity, and the control cavity discharges air outwards. At this time, the gas in the energy storage cavity pushes the valve core away from the cylinder barrel and enters the cylinder barrel to realize pushing the piston to form a firing.

[0015] In this solution, when the control valve is in the first state, the compressed air in the air supply cavity enters the energy storage cavity and the control cavity at the same time. The valve core is pressed against the end of the cylinder barrel under the combined action of the elastic element and the compressed gas in the control cavity, so as to realize that the gas pressure is basically in an equilibrium state before injection;

[0016] Then the control valve is switched to the second state. The compressed air in the air supply cavity stops flowing into the control cavity, and the compressed air in the control cavity is discharged outwards. Therefore, the balance between the energy storage cavity and the control cavity of the valve core is broken, and the pressure of the compressed air in the control cavity becomes smaller, that is, the backward thrust of the compressed air in the energy storage cavity on the valve core > the forward thrust of the compressed air and the elastic element in the control cavity on the valve core. The valve core will be pushed backward by the compressed air in the energy storage cavity, and the end opening of the cylinder barrel will be opened accordingly. Once there is a little gap between the cylinder barrel and the valve core, the compressed air in the energy storage cavity will enter the cylinder barrel and act on the entire front end face of the valve core. The valve core quickly moves away from the cylinder barrel. At the same time, the compressed air in the energy storage cavity instantly enters the cylinder barrel, pushes the piston in the cylinder barrel, and the piston then impacts the push rod and drives the push rod to move. The push rod high-speed ejects the liquid medicine in the barrel assembly to complete the injection.

[0017] The valve core of the present invention has a fast opening speed, the gas directly enters the cylinder barrel from the energy storage cavity, the gas path is short, and the impact effect is good. Therefore, the impact force is large.

[0018] Further, a part of the valve core against the surface where the cylinder barrel is located is located in the energy storage cavity; thus, after the control cavity exhausts air outwards, the compressed air in the energy storage cavity can push the part of the valve core located in the energy storage cavity, causing the valve core to move towards the control cavity, so as to respond to the piston firing when the control valve switches from the first state to the second state; meanwhile, it is beneficial that in the first state, the compressed air in the control cavity firmly presses the valve core against the end of the cylinder barrel, realizing the seal between the valve core and the end face of the cylinder barrel.

[0019] For the convenience of manufacturing, further, an air supply cavity is formed between the outer peripheral surface of the cylinder barrel, the inner peripheral surface of the inner cavity and the front end of the valve core.

[0020] Further, a first sealing gasket for abutting against the end of the cylinder barrel is provided on the front side surface of the valve core; by sealing between the valve core and the cylinder barrel through the first sealing gasket, it can prevent the gas in the energy storage cavity from leaking into the cylinder barrel in the first state, ensuring that the compressed air in the energy storage cavity can be stored to the set pressure.

[0021] For the convenience of manufacturing and assembly, further, an end cover is fixed to the rear end of the housing, and a control cavity is formed between the end cover and the rear end of the valve core.

[0022] In order to realize that the piston can automatically reset after injection, improve the convenience of use and the injection efficiency, further, a reset cavity is further included. In this embodiment, the reset cavity is formed between the outer peripheral surface and the inner peripheral surface of the cylinder barrel. A reset air inlet hole and a reset air outlet hole are provided at the front end of the cylinder barrel. Both the reset air inlet hole and the reset air outlet hole are communicated with the reset cavity. The reset air outlet hole is located on the front side of the reset air inlet hole. When the piston fires, the reset air outlet hole is located on the front side of the piston;

[0023] The piston divides the inside of the cylinder barrel into a rodless cavity and a rod cavity. The push rod and the rod cavity are both on the same side of the piston. A first exhaust hole is communicated with the rodless cavity. When the control valve is in the second state, the valve core moves away from the cylinder barrel and blocks the first exhaust hole. When the control valve is in the first state, the valve core moves closer to the cylinder barrel, and the first exhaust hole is conducted;

[0024] At the initial stage of piston firing, both the reset air inlet hole and the reset air outlet hole are located in the rod cavity. The compressed air in the energy storage cavity instantaneously enters the rodless cavity and forces the valve core to move towards the control cavity, and the first elastic element is compressed. Therefore, the first exhaust hole will be blocked by the valve core. As the piston moves towards the rod cavity direction, the reset air inlet hole changes to be located in the rodless cavity, and the compressed air in the rodless cavity will enter the reset cavity from the reset air inlet hole and be stored in the reset cavity for piston reset;

[0025] After the piston is fired, the control valve switches to the first state, and the air supply chamber resumes supplying compressed air into the control chamber. The compressed air in the control chamber, in cooperation with the elastic force of the first elastic element, pushes the valve core towards the cylinder barrel again and seals the end of the cylinder barrel. The first exhaust hole resumes conduction. At this time, the compressed air (equivalent to waste gas) in the rodless chamber is discharged to the outside through the first exhaust hole, and the pressure in the rodless chamber decreases. Part of the compressed air in the reset chamber flows into the rod chamber through the reset air outlet hole, and the other part flows into the rodless chamber through the reset air inlet hole and is discharged from the first exhaust hole. After the piston moves a certain distance towards the valve core, the reset air inlet hole enters the rod chamber, and supplies air to the rod chamber together with the reset air outlet hole, realizing the reset of the piston.

[0026] To ensure the stable reset of the piston, further, the cross-sectional area of the reset air outlet hole > the cross-sectional area of the reset air inlet hole; so that when the piston starts to reset, most of the compressed air stored in the reset chamber enters the rod chamber, ensuring the smooth reset of the piston.

[0027] Further, a communication hole penetrates through the valve core. The rodless chamber is communicated with the first exhaust hole through the communication hole. An extension part protrudes from the rear end of the piston, and the extension part extends into the communication hole, and a gap is formed between the extension part and the communication hole; by using the setting of the extension part, the exhaust volume from the first exhaust hole when the compressed gas in the energy storage chamber initially enters the cylinder barrel can be reduced.

[0028] Further, an annular sealing section for blocking or opening the first exhaust hole protrudes from the rear end of the valve core;

[0029] When the control valve is in the first state, the valve core abuts against the end of the cylinder barrel, and the sealing section of the valve core opens the first exhaust hole;

[0030] When the control valve is in the second state, the valve core is away from the cylinder barrel, and the sealing section of the valve core blocks the first exhaust hole; in this way, when the valve core switches between the first state and the second state, the sealing section thereon can move accordingly to automatically open or block the first exhaust hole.

[0031] Further, a second sealing pad for abutting against the rear end of the sealing section of the valve core is provided at one end of the control chamber away from the valve core; when the piston is fired, the rear end of the sealing section abuts against the second sealing pad, so that when the piston is fired, the first exhaust hole can be reliably blocked, improving the sealing performance and reducing the loss of compressed air used for firing.

[0032] Further, the first elastic element is located within the sealing section. One end of the first elastic element abuts against the valve core, and the other end abuts against the end cap. By arranging the first elastic element within the sealing section, the space utilization rate can be improved, the structure can be made more compact, and at the same time, the first elastic element can be designed to be longer to increase the elastic working range of the first elastic element, thereby enhancing the elasticity.

[0033] Further, the first elastic element is a spring.

[0034] Further, a second exhaust hole is communicated inside the cylinder barrel, and the second exhaust hole is on the same side of the piston as the push rod. The second exhaust hole is mainly used for exhausting gas when the piston is fired, enabling the piston to smoothly reach the forefront of the firing stroke and discharging the reset waste gas to facilitate the next firing.

[0035] Further, the control valve includes a valve stem, a valve seat and a valve body. The valve body is fixed on the housing, the valve seat is installed inside the valve body, and the valve seat has a valve cavity and a control hole. The valve body has a valve stem hole, an inlet and an outlet. The valve cavity is communicated with the inlet of the valve body through the control hole, and the valve cavity is communicated with the outlet of the valve body. The valve stem is movably installed in the valve stem hole, and there is an exhaust gap on the valve body. A blocking portion is fixed at the inner end of the valve stem;

[0036] When the valve stem approaches the control hole, the blocking portion blocks the control hole, and the outlet of the valve body is communicated with the exhaust gap; when the valve stem moves away from the control hole, the blocking portion blocks the exhaust gap, and the inlet of the valve body is communicated with the outlet of the valve body through the control hole;

[0037] The inlet of the valve body and the outlet of the valve body are connected in series on the connecting flow path;

[0038] Under normal conditions, the blocking portion of the valve stem is away from the control hole under the action of compressed air in the air supply cavity, and the control valve is in the first state, and the outlet and the inlet of the valve body are communicated; when the valve stem is manually driven to move into the valve body, the blocking portion of the valve stem blocks the control hole, but the blocking portion will be separated from the exhaust gap. Therefore, the outlet of the valve body is switched to be communicated with the exhaust gap. At this time, the control valve is in the second state.

[0039] Further, a trigger is hinged on the housing, and the trigger is arranged opposite to the outer end of the valve body; by pulling the trigger, the valve stem can be driven to move, which is convenient for operation.

[0040] Further, a second elastic element is arranged between the trigger and the valve body. One end of the second elastic element abuts against the trigger, and the other end abuts against the valve body; when the trigger is pulled, the second elastic element will be compressed, and after the trigger is released, the trigger automatically resets under the action of the second elastic element.

[0041] Furthermore, the exhaust gap is formed between the outer circumferential surface of the valve stem and the inner circumferential surface of the valve stem hole; thereby, the structure can be simplified and the manufacturing is facilitated.

[0042] Furthermore, the control valve is a manual two-position three-way valve, an electric two-position three-way valve or a pneumatic two-position three-way valve; the two working positions of the two-position three-way valve correspond to the first state and the second state respectively.

[0043] Further, a buckle is fixedly connected to the piston, a flange is provided at the rear end of the push rod, a channel matching the flange is provided in the buckle, a mounting hole is provided at the front end of the buckle for the push rod to pass through, the mounting hole is communicated with the channel, and a step surface is formed between the mounting hole and the channel, a first notch is provided above the mounting hole, a second notch is provided at the front end of the channel, and the first notch and the second notch are communicated;

[0044] The push rod is located in the mounting hole, the flange is located in the channel, and the front end surface of the flange is opposite to the step surface.

[0045] The push rod can be hooked by the buckle to prevent it from falling off the piston, and the push rod is tilted upward, and the flange on the push rod will fall off from the second notch and the channel, so that the push rod can be quickly disassembled, thereby facilitating regular disassembly, cleaning and disinfection of the push rod.

[0046] Furthermore, the front end portion of the buckle has a guide surface for guiding the flange into the channel 1601, and the guide surface is inclined inward from front to back; when the push rod is installed, the push rod 5 can be directly inserted into the cylinder, and when the flange at the rear end of the push rod reaches the front end portion of the buckle, it will first contact the guide surface of the buckle, and the flange will move along the guide surface toward the second notch and fall into the channel of the buckle from the second notch 1605, thereby facilitating the installation of the push rod and improving the convenience of use.

[0047] Furthermore, the barrel assembly includes a barrel and a locking nut, the end of the push rod away from the piston is slidably installed in the barrel, the rear end of the outer peripheral surface of the barrel has a protrusion, the locking nut is sleeved outside the barrel, the end of the locking nut away from the shell has a bottom edge, and the protrusion has a limiting structure;

[0048] The rear end of the gun barrel is inserted into the connecting section at the front end of the shell, the locking nut is threadedly connected to the shell, and the bottom edge of the locking nut abuts against the limiting structure on the protruding part, and the front end face of the connecting section abuts against the rear end face of the protruding part;

[0049] When the locking nut is tightened on the connecting section of the shell, the gun barrel is clamped and fixed on the shell, so as to avoid the problem that the injection port of the gun barrel is easily skewed due to the threaded connection of the gun barrel on the shell.

[0050] The beneficial effects of the present invention are as follows: The needleless syringe of the present invention has a fast opening speed of its control valve, a short gas path and a large gas path channel for the compressed gas in the energy storage cavity to enter the cylinder barrel, effectively realizing the impact effect of the piston, and further realizing the high-pressure firing of the liquid medicine under the action of low-pressure compressed air, greatly reducing the use cost, having a high safety factor and good market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The present invention will be further described below with reference to the drawings and embodiments.

[0052] Figure 1 is a schematic cross-sectional view of the needleless syringe of the present invention;

[0053] Figure 2 is Figure 1 a partial enlarged schematic view of A in

[0054] Figure 3 is Figure 1 a partial enlarged schematic view of B in

[0055] Figure 4 is Figure 1 a partial enlarged schematic view of C in

[0056] Figure 5 is a three-dimensional schematic view of the needleless syringe of the present invention;

[0057] Figure 6 is a schematic view of the needleless syringe of the present invention when firing;

[0058] Figure 7 is a schematic view of the needleless syringe of the present invention after firing;

[0059] Figure 8 is Figure 7 a partial enlarged schematic view of D in

[0060] Figure 9 is a schematic view of the needleless syringe of the present invention when resetting;

[0061] Figure 10 is a schematic view of the connection between the piston and the push rod in the needleless syringe of the present invention;

[0062] Figure 11 is a schematic view of the buckle in the needleless syringe of the present invention.

[0063] In the figure: 1. Housing, 101. Air supply cavity, 102. Second exhaust hole, 103. Connection section;

[0064] 2. Cylinder barrel, 201. Reset intake hole, 202. Reset outlet hole, 203. Rodless cavity, 204. Rod cavity;

[0065] 3. Barrel assembly, 301. Barrel, 3011. Protrusion, 302. Locking nut, 3021. Bottom edge, 303. Limiting structure, 304. Injection head, 305. Injection one-way valve, 306. Liquid injection one-way valve;

[0066] 4. Piston, 401. Extension;

[0067] 5. Push rod, 501. Flange;

[0068] 6. Energy storage chamber, 7. Control chamber;

[0069] 8. Spool valve, 801. Communication hole, 802. Sealing section;

[0070] 9. Control valve; 901. Valve stem, 9011. Blocking part, 9012. Seal; 902. Valve body, 9021. Valve stem hole, 9022. Inlet, 9023. Outlet, 9024. Exhaust gap; 903. Valve seat, 9031. Valve cavity, 9032. Control hole, 904. Trigger, 905. Second elastic element;

[0071] 10. First elastic element, 11. Connecting flow path, 12. First gasket;

[0072] 13. End cap, 1301. First exhaust hole;

[0073] 14. Reset cavity, 15. Second gasket;

[0074] 16. Buckle, 1601. Channel, 1602. Mounting hole, 1603. Step surface, 1604. First notch, 1605. Second notch, 1606. Guide surface;

[0075] 17. Silencer;

[0076] 18. Third gasket. Detailed implementation mode

[0077] Now, the present invention will be further described in detail with reference to the accompanying drawings. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present invention in a schematic manner. Therefore, they only show the components related to the present invention. Directions and references (such as up, down, left, right, etc.) can only be used to assist in the description of the features in the drawings. Therefore, the following specific implementation modes are not adopted in a restrictive sense, and the scope of the claimed subject matter is only defined by the appended claims and their equivalent forms.

[0078] Embodiment 1

[0079] As Figures 1 - 11 shown, a needleless syringe includes:

[0080] The housing 1 has an inner cavity and an air supply chamber 101, and a cylinder 2 is arranged in the inner cavity;

[0081] The barrel assembly 3 is used for placing the liquid medicine;

[0082] The piston 4 is slidably installed in the cylinder 2, and a push rod 5 for pushing the liquid medicine in the barrel assembly 3 is drivingly connected to the piston 4;

[0083] The energy storage chamber 6 is communicated with the air supply chamber 101;

[0084] The control chamber 7 is communicated with the air supply chamber 101;

[0085] The balance valve has a valve core 8 and a first elastic element 10 for pressing the valve core 8 against the end of the cylinder 2. The first elastic element 10 is a spring. The energy storage chamber 6 and the control chamber 7 are respectively located on both sides of the valve core 8;

[0086] And the control valve 9 is arranged on the connecting flow path 11 between the control chamber 7 and the air supply chamber 101. The control valve 9 has a first state and a second state. In the first state, the connecting flow path 11 is communicated, and the control valve 9 allows the gas in the air supply chamber 101 to enter the control chamber 7, and the valve core 8 remains pressed against the end of the cylinder 2; in the second state, the connecting flow path 11 is cut off, the control valve 9 blocks the gas in the air supply chamber 101 from entering the control chamber 7, and the control chamber 7 discharges air outwards. At this time, the gas in the energy storage chamber 6 pushes the valve core 8 away from the cylinder 2 and enters the cylinder 2 to realize pushing the piston 4 to form a firing.

[0087] In this embodiment, the air supply chamber 101 is kept communicated with the energy storage chamber 6.

[0088] In this embodiment, a part of the surface where the valve core 8 abuts against the cylinder 2 is located in the energy storage chamber 6; thus, after the control chamber 7 discharges air outwards, the compressed air in the energy storage chamber 6 can push the part of the valve core 8 located in the energy storage chamber 6, so that the valve core 8 moves towards the control chamber 7 to respond to the piston 4 firing when the control valve 9 switches from the first state to the second state; at the same time, it is beneficial that in the first state, the compressed air in the control chamber 7 firmly presses the valve core 8 against the end of the cylinder 2, so that the compressed air in the energy storage chamber 6 can stably continue to increase the pressure.

[0089] In this embodiment, an air supply chamber 101 is formed between the outer peripheral surface of the cylinder barrel 2, the inner peripheral surface of the inner cavity, and the front end of the valve core 8; for the convenience of manufacturing and assembly, an end cover 13 is fixed to the rear end of the housing 1, and a control chamber 7 is formed between the end cover 13 and the rear end of the valve core 8; it should be noted that there are various ways to form the air supply chamber 101 and the control chamber 7. For example, if the housing 1 is a split half structure, the control chamber 7 is formed between the valve core 8 and the rear end inside the housing 1; it can also be that an end cover 13 is provided at the front end of the housing 1, and the control chamber 7 is formed between the valve core 8 and the rear end inside the housing 1; no restrictions are imposed on the shape and formation method of the air supply chamber 101 and the control chamber 7 herein. As long as the above-mentioned positional relationship is satisfied among the air supply chamber 101, the valve core 8, and the control chamber 7, it is regarded as the protected content of the present invention.

[0090] In this embodiment, a first sealing gasket 12 for abutting against the end of the cylinder barrel 2 is provided on the front side surface of the valve core 8; by sealing between the valve core 8 and the cylinder barrel 2 through the first sealing gasket 12, it can prevent the compressed air in the energy storage chamber 6 from leaking into the cylinder barrel 2 in the first state, ensuring that the compressed air in the energy storage chamber 6 can be stored to the set pressure; during specific installation, the first sealing gasket 12 can be fixedly installed on the valve core 8 and move together with the valve core 8, or the first sealing gasket 12 can also be fixedly installed at the rear end of the cylinder barrel 2.

[0091] In order to enable the piston 4 to automatically reset after injection and improve the convenience of use and injection efficiency, this embodiment further includes a reset chamber 14. The reset chamber 14 is partitioned and not communicated with both the energy storage chamber 6 and the air supply chamber 101. A reset air inlet hole 201 and a reset air outlet hole 202 are opened at the front end of the cylinder barrel 2. Both the reset air inlet hole 201 and the reset air outlet hole 202 are communicated with the reset chamber 14. The reset air outlet hole 202 is located in front of the reset air inlet hole 201. When the piston 4 is fired, the reset air outlet hole 202 is located in front of the piston 4.

[0092] The piston 4 divides the inside of the cylinder barrel 2 into a rodless chamber 203 and a rod chamber 204. The push rod 5 and the rod chamber 204 are both on the same side of the piston 4. A first exhaust hole 1301 is communicated with the rodless chamber 203. The first exhaust hole 1301 can be specifically opened on the end cover 13 to improve the compactness of the structure. When the control valve 9 is in the second state, the valve core 8 is away from the cylinder barrel 2 and blocks the first exhaust hole 1301. When the control valve 9 is in the first state, the valve core 8 approaches the cylinder barrel 2, and the first exhaust hole 1301 is conducted.

[0093] Such as Figure 6 、 7As shown in FIGS. 8 and 9 , when the piston 4 is initially fired, the reset air inlet 201 and the reset air outlet 202 are both located in the rod chamber 204, and the compressed air in the energy storage chamber 6 instantly enters the rodless chamber 203, and forces the valve core 8 to move toward the control chamber 7, and the first elastic element 10 is compressed, so the first exhaust hole 1301 is blocked by the valve core 8, and as the piston 4 moves toward the rod chamber 204, the reset air inlet 201 is transformed to be located in the rodless chamber 203, and the compressed air in the rodless chamber 203 enters the reset chamber 14 from the reset air inlet 201, and is stored in the reset chamber 14, for resetting the piston 4;

[0094] like Figure 1 and 7 As shown, in this embodiment, the front end portion of the inner cavity of the shell 1 has a third sealing gasket 18 for contacting the piston 4 after firing. After firing, the left end surface of the piston 4 contacts the third sealing gasket 18. Therefore, at this time, the compressed gas in the reset chamber 14 cannot leak to the outside through the second exhaust hole 102.

[0095] After the piston 4 is fired, the control valve 9 switches to the first state, and the air supply chamber 101 re-supplies compressed air into the control chamber 7. The compressed air in the control chamber 7 cooperates with the elastic force of the first elastic element 10 to push the valve core 8 to move toward the cylinder 2 again and block the end of the cylinder 2. The first exhaust hole 1301 is restored to conduction. At this time, the compressed air (equivalent to the exhaust gas) in the rodless chamber 203 is discharged to the outside through the first exhaust hole 1301, and the pressure in the rodless chamber 203 decreases. Most of the compressed air in the reset chamber 14 flows into the rod chamber 204 through the reset air outlet hole 202, and a small part flows into the rodless chamber 203 through the reset air inlet hole 201 and is discharged from the first exhaust hole 1301.

[0096] like Figure 3 As shown, in order to ensure that the piston 4 can be reset stably, the cross-sectional area of the reset air outlet 202 in this embodiment is greater than the cross-sectional area of the reset air inlet 201; so that when the piston 4 is initially reset, most of the compressed air stored in the reset chamber 14 enters the rod chamber 204, ensuring that the piston 4 is reset smoothly;

[0097] like Figure 1 and 2 As shown, in this embodiment, a connecting hole 801 is passed through the valve core 8, and the rodless chamber 203 is connected with the first exhaust hole 1301 through the connecting hole 801. The rear end of the piston 4 protrudes with an extension portion 401, and the extension portion 401 extends into the connecting hole 801, and a gap is formed between the extension portion 401 and the connecting hole 801; by setting the extension portion 401, the exhaust amount from the first exhaust hole 1301 when the compressed gas in the energy storage chamber 6 initially enters the cylinder 2 can be reduced;

[0098] likeFigure 2 As shown, a ring-shaped sealing section 802 for blocking or opening the first exhaust hole 1301 protrudes from the rear end of the valve core 8;

[0099] When the control valve 9 is in the first state, the valve core 8 abuts against the end of the cylinder barrel 2, and the sealing section 802 of the valve core 8 opens the first exhaust hole 1301;

[0100] When the control valve 9 is in the second state, the valve core 8 moves away from the cylinder barrel 2, and the sealing section 802 of the valve core 8 blocks the first exhaust hole 1301; thus, when the valve core 8 switches between the first state and the second state, the sealing section 802 thereon can move accordingly to automatically open or block the first exhaust hole 1301.

[0101] As Figure 2 and 6 shown, in this embodiment, a second sealing gasket 15 for abutting against the rear end of the sealing section 802 of the valve core 8 is provided at one end of the control cavity 7 away from the valve core 8; when the piston 4 is fired, the rear end of the sealing section 802 abuts against the second sealing gasket 15, so that when the piston 4 is fired, the first exhaust hole 1301 can be reliably blocked, reducing the loss of compressed air used for firing.

[0102] As Figure 1 and 2 shown, in this embodiment, the first elastic element 10 is located inside the sealing section 802, one end of the first elastic element 10 abuts against the valve core 8, and the other end abuts against the end cover 13; by arranging the first elastic element 10 inside the sealing section 802, the space utilization rate can be improved, the structure is more compact, and at the same time, the first elastic element 10 can be designed to be longer, increasing the elastic working range of the first elastic element 10 to enhance the elasticity.

[0103] As Figure 1 shown, in this embodiment, a second exhaust hole 102 is communicated inside the cylinder barrel 2, and the second exhaust hole 102 is specifically arranged at the front end of the housing 1, and the second exhaust hole 102 is on the same side of the piston 4 as the push rod 5; the second exhaust hole 102 is mainly used for exhausting when the piston 4 is fired, enabling the piston 4 to smoothly reach the front end of the firing stroke; and exhausting the waste gas in the return cavity 14 and the rodless cavity 204 to facilitate the next firing.

[0104] As Figure 3As shown in the figure, in this embodiment, the control valve 9 includes a valve stem 901, a valve seat 903 and a valve body 902. The valve body 902 is fixed on the housing 1. The valve seat 903 is installed in the valve body 902. The valve seat 903 has a valve cavity 9031 and a control hole 9032. The valve body 902 has a valve stem hole 9021, an inlet 9022 and an outlet 9023. The valve cavity 9031 is communicated with the inlet 9022 of the valve body 902 through the control hole 9032. The valve cavity 9031 is communicated with the outlet 9023 of the valve body 902. The valve stem 901 is movably installed in the valve stem hole 9021, and the valve body 902 has an exhaust gap 9024. A blocking portion 9011 is fixed at the inner end of the valve stem 901;

[0105] When the valve stem 901 approaches the control hole 9032, the blocking portion 9011 blocks the control hole 9032, and the outlet 9023 of the valve body 902 is communicated with the exhaust gap 9024. When the valve stem 901 moves away from the control hole 9032, the blocking portion 9011 blocks the exhaust gap 9024, and the inlet 9022 of the valve body 902 is communicated with the outlet 9023 of the valve body 902 through the control hole 9032. In this embodiment, a sealing member 9012 can be arranged between the blocking portion 9011 and the valve body 902, so that when the valve stem 901 moves away from the control hole 9032, the blocking portion 9011 can better block the exhaust gap 9024 and improve the sealing performance of the exhaust gap 9024;

[0106] The inlet 9022 of the valve body 902 and the outlet 9023 of the valve body 902 are connected in series on the connecting flow path 11;

[0107] Under normal conditions, the blocking portion 9011 of the valve stem 901 moves away from the control hole 9032 under the action of compressed air in the air supply cavity 101, and the control valve 9 is in the first state, and the outlet 9023 and the inlet 9022 of the valve body 902 are communicated. When the valve stem 901 is driven by hand to move into the valve body 902, the blocking portion 9011 of the valve stem 901 blocks the control hole 9032, but the blocking portion 9011 will be separated from the exhaust gap 9024. Therefore, the outlet 9023 of the valve body 902 is switched to be communicated with the exhaust gap 9024. At this time, the control valve 9 is in the second state.

[0108] As Figure 3 shown in the figure, in this embodiment, a trigger 904 is hinged on the housing 1, and the trigger 904 is arranged opposite to the outer end of the valve body 902; By pulling the trigger 904, the valve stem 901 can be driven to move, which is convenient for operation;

[0109] As Figure 3As shown, in this embodiment, a second elastic element 905 is provided between the trigger 904 and the valve body 902. The second elastic element 905 can be specifically a spring. One end of the second elastic element 905 abuts against the trigger 904, and the other end abuts against the valve body 902. When the trigger 904 is pulled, the second elastic element 905 will be compressed. After the trigger 904 is released, the trigger 904 automatically resets under the action of the second elastic element 905.

[0110] like Figure 3 As shown, in this embodiment, the exhaust gap 9024 is formed between the outer circumference of the valve stem 901 and the inner circumference of the valve stem hole 9021; thereby simplifying the structure and facilitating manufacturing;

[0111] Alternatively, the control valve 9 of this embodiment is a manual two-position three-way valve, an electric two-position three-way valve or a pneumatic two-position three-way valve; the two working positions of the two-position three-way valve correspond to the first state and the second state respectively, that is, the two-position three-way valve has three ports, namely, an air intake outlet, an air intake inlet and an exhaust outlet, the exhaust outlet is connected to the outside, and the air intake outlet and the air intake inlet are connected in series on the connecting flow path 11.

[0112] like Figure 2 , 10 As shown in Figures 11 and 12, in this embodiment, a buckle 16 is fixedly connected to the piston 4, the rear end of the push rod 5 has a flange 501, the buckle 16 has a channel 1601 matching the flange 501, the front end of the buckle 16 has a mounting hole 1602 for the push rod 5 to pass through, the mounting hole 1602 is connected to the channel 1601, and a step surface 1603 is formed between the mounting hole 1602 and the channel 1601, a first notch 1604 is opened above the mounting hole 1602, and a second notch 1605 is opened at the front end of the channel 1601, and the first notch 1604 and the second notch 1605 are connected;

[0113] The push rod 5 is located in the mounting hole 1602 , the flange 501 is located in the channel 1601 , and the front end surface of the flange 501 is opposite to the step surface 1603 .

[0114] In the reset state, there is a certain distance between the right end of the push rod 5 and the right end of the channel 1601 in the buckle 16 to achieve the impact of the piston 4 on the push rod 5.

[0115] The push rod 5 can be hooked by the buckle 16 to prevent it from falling off the piston 4, and the push rod 5 can be tilted upward so that the flange 501 on the push rod 5 will fall off from the second notch 1605 and the channel 1601, thereby achieving rapid disassembly of the push rod 5, thereby facilitating regular disassembly, cleaning and disinfection of the push rod 5.

[0116] In this embodiment, the front end of the buckle 16 has a guiding surface 1606 for guiding the flange 501 into the channel 1601. The guiding surface 1606 is inclined inwards from front to back. When installing the push rod 5, the push rod 5 can be directly inserted into the cylinder barrel 2. When the flange 501 at the rear end of the push rod 5 reaches the front end of the buckle 16, it will first contact the guiding surface 1606 of the buckle 16. The flange 501 will move towards the second notch 1605 along the guiding surface 1606 and fall into the channel 1601 of the buckle 16 from the second notch 1605, thus facilitating the installation of the push rod 5 and improving the convenience of use.

[0117] As Figure 1 and 4 shown, in this embodiment, the barrel assembly 3 includes a barrel 301 and a locking nut 302. One end of the push rod 5 away from the piston 4 is slidably installed in the barrel 301. The rear end of the outer peripheral surface of the barrel 301 has a protruding portion 3011. The locking nut 302 is sleeved outside the barrel 301. One end of the locking nut 302 away from the housing 1 has a bottom edge 3021. The protruding portion 3011 has a limiting structure 303.

[0118] The rear end of the barrel 301 is inserted into the connecting section 103 at the front end of the housing 1. The locking nut 302 is threadedly connected to the housing 1, and the bottom edge 3021 of the locking nut 302 abuts against the limiting structure 303 on the protruding portion 3011. The front end face of the connecting section 103 abuts against the rear end face of the protruding portion 3011. In this embodiment, the limiting structure 303 can specifically adopt a circlip, and the circlip is stuck on the protruding portion 3011.

[0119] When the locking nut 302 is tightened on the connecting section 103 of the housing 1, the barrel 301 is clamped and fixed on the housing 1, avoiding the problem that the liquid injection port of the barrel 301 is prone to skew caused by the threaded connection of the barrel 301 to the housing 1.

[0120] As Figure 1 shown, in this embodiment, the front end of the barrel 301 has an injection head 304, an injection one-way valve 305, and a liquid injection one-way valve 306 installed at the liquid injection port. A storage space for storing the liquid medicine is formed between the liquid injection one-way valve 306 and the push rod 5 in the barrel 301, and the liquid injection one-way valve 306 is communicated with the storage space.

[0121] As Figure 2 shown, in order to reduce the noise during exhaust, a silencer 17 can be provided on the communication path between the communication hole 801 and the first exhaust hole 1301. The silencer 17 is a porous material, such as porous copper foam, etc. A sound insulation structure can also be installed at the second exhaust hole 102 to reduce the noise.

[0122] The working principle of the needleless syringe in this embodiment is as follows:

[0123] The compressor supplies air to the air supply chamber 101;

[0124] As Figure 3 shown, initially, the blocking portion 9011 of the valve stem 901 moves away from the control hole 9032 under the action of the compressed air in the air supply chamber 101, the control valve 9 is in the first state, the outlet 9023 and the inlet 9022 of the valve body 902 are communicated, and the compressed air in the air supply chamber 101 enters the energy storage chamber 6 and the control chamber 7 at the same time. The valve core 8 abuts against the end of the cylinder barrel 2 under the combined action of the first elastic element 10 and the gas pressure in the control chamber 7;

[0125] As Figure 6 shown, after pulling the trigger 904, when the valve stem 901 moves into the valve body 902, the blocking portion 9011 of the valve stem 901 blocks the control hole 9032, but the blocking portion 9011 will separate from the exhaust gap 9024. Therefore, the outlet 9023 of the valve body 902 is switched to communicate with the exhaust gap 9024. At this time, the control valve 9 is in the second state, the compressed air in the air supply chamber 101 stops flowing into the control chamber 7, and the compressed air in the control chamber 7 is discharged outward through the exhaust gap 9024 of the control valve 9. Therefore, the balance between the energy storage chamber 6 and the control chamber 7 for the valve core 8 is broken, and the pressure of the compressed air in the control chamber 7 becomes smaller, that is, the backward thrust of the compressed air in the energy storage chamber 6 on the valve core 8 > the forward thrust of the compressed air in the control chamber 7 and the elastic element 10 on the valve core 8. The valve core 8 will be pushed backward by the compressed air in the energy storage chamber 6, and the end opening of the cylinder barrel 2 will be opened accordingly. Once there is a little gap between the cylinder barrel 2 and the valve core 8, the compressed air in the energy storage chamber 6 will enter the cylinder barrel 2 and act on the entire front end face of the valve core 8. The valve core 8 quickly moves away from the cylinder barrel 2. At the same time, the compressed air in the energy storage chamber 6 instantly enters the rodless chamber 203 of the cylinder barrel 2, pushes the piston 4 in the cylinder barrel 2, and the piston 4 hits the push rod 5 and drives the push rod 5 to move forward. The push rod 5 pushes the liquid medicine in the gun barrel 301 out at high speed to complete the injection;

[0126] Among them, as Figure 7 、 8 and shown in 9, when the piston 4 is initially fired, both the reset air inlet hole 201 and the reset air outlet hole 202 are located in the rod chamber 204. The compressed air in the energy storage chamber 6 instantly enters the rodless chamber 203 and forces the valve core 8 to move towards the control chamber 7, and the first elastic element 10 is compressed. Therefore, the first exhaust hole 1301 will be blocked by the valve core 8. As the piston 4 moves towards the rod chamber 204, the reset air inlet hole 201 changes to be located in the rodless chamber 203, and the compressed air in the rodless chamber 203 will enter the reset chamber 14 from the reset air inlet hole 201 and be stored in the reset chamber 14 for resetting the piston 4;

[0127] After the piston 4 is fired, the trigger 904 is released, and the control valve 9 automatically returns to the first state. The air supply chamber 101 supplies compressed air into the control chamber 7 again. The compressed air in the control chamber 7, in cooperation with the elastic force of the first elastic element 10, pushes the valve core 8 towards the cylinder barrel 2 again and seals the end of the cylinder barrel 2. The first exhaust hole 1301 is restored to conduction. At this time, the compressed air (equivalent to waste gas) in the rodless chamber 203 is discharged to the outside through the first exhaust hole 1301, and the pressure in the rodless chamber 203 becomes smaller. Part of the compressed air in the return chamber 14 enters the rod chamber 204 through the return air outlet hole 202, and the other part flows into the rodless chamber 203 through the return air inlet hole 201 and is discharged from the first exhaust hole 1301. When the thrust of the gas in the rod chamber 204 on the piston 4 is greater than the thrust of the gas in the rodless chamber 203 on the piston 4, the piston 4 leaves the third gasket 18, and the gas in the rod chamber 204 acts on the entire left end face of the piston 4 to quickly reset the piston 4; among them, at the initial stage of resetting, the gas in the rod chamber 204 only acts on a part of the area of the piston 4, and then acts on the entire left end face of the piston 4. After the piston 4 moves a certain distance towards the valve core 8, the return air inlet hole 201 enters the rod chamber 204 accordingly, and supplies air to the rod chamber 204 together with the return air outlet hole 202 to realize the reset of the piston 4. And the aperture of the return air outlet hole 202 > the aperture of the return air inlet hole 201, so that most of the compressed air stored in the return chamber 14 enters the rod chamber 204 through the return air inlet hole 201 to ensure the smooth reset of the piston 4.

[0128] Based on the inspiration of the ideal embodiment of the present invention described above, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A needleless syringe, characterized in that: Comprising: A housing (1) having an inner cavity and a gas supply cavity (101), and a cylinder barrel (2) is disposed in the inner cavity; A barrel assembly (3) for placing a liquid medicine; A piston (4) slidably mounted in the cylinder barrel (2), and a push rod (5) for pushing the liquid medicine in the barrel assembly (3) is drivingly connected to the piston (4); An energy storage cavity (6) communicating with the gas supply cavity (101); A control cavity (7) communicating with the gas supply cavity (101); A balance valve having a valve core (8) and a first elastic element (10) for pressing the valve core (8) against the end of the cylinder barrel (2), and the energy storage cavity (6) and the control cavity (7) are respectively located on both sides of the valve core (8); And a control valve (9) disposed on a connection flow path (11) between the control cavity (7) and the gas supply cavity (101). The control valve (9) has a first state and a second state. In the first state, the connection flow path (11) is communicated, and the control valve (9) allows the gas in the gas supply cavity (101) to enter the control cavity (7), and the valve core (8) remains pressed against the end of the cylinder barrel (2); in the second state, the connection flow path (11) is cut off, the control valve (9) blocks the gas in the gas supply cavity (101) from entering the control cavity (7), and discharges the gas in the control cavity (7) to the outside. At this time, the gas in the energy storage cavity (6) pushes the valve core (8) away from the cylinder barrel (2), and the gas enters the cylinder barrel (2) to realize pushing the piston (4) to form a firing; When the control valve (9) is in the first state, the compressed air in the gas supply cavity (101) enters the energy storage cavity (6) and the control cavity (7) simultaneously, and the valve core (8) is pressed against the end of the cylinder barrel (2) under the combined action of the first elastic element (10) and the gas pressure in the control cavity (7); When the control valve (9) is switched to the second state, the backward thrust of the compressed air in the energy storage cavity (6) on the valve core (8) is greater than the forward thrust of the compressed air in the control cavity (7) and the first elastic element (10) on the valve core (8).

2. The needleless injector according to claim 1, wherein: A part of the surface where the valve core (8) abuts against the cylinder barrel (2) is located in the energy storage cavity (6).

3. The needleless injector according to claim 1, wherein: The gas supply cavity (101) is formed between the outer peripheral surface of the cylinder barrel (2), the inner peripheral surface of the inner cavity of the housing (1), and the front end of the valve core (8).

4. The needleless injector according to claim 1, wherein: A first sealing gasket (12) for abutting against the end of the cylinder barrel (2) is provided on the front side surface of the valve core (8).

5. The needleless injector according to claim 1, wherein: An end cover (13) is fixed to the rear end of the housing (1), and the control cavity (7) is formed between the end cover (13) and the rear end of the valve core (8).

6. The needleless injector according to claim 1, characterized in that: It further includes a reset cavity (14). A reset air inlet hole (201) and a reset air outlet hole (202) are opened at the front end of the cylinder barrel (2). The reset air inlet hole (201) and the reset air outlet hole (202) are both communicated with the reset cavity (14). The reset air outlet hole (202) is located in front of the reset air inlet hole (201). When the piston (4) is fired, the reset air outlet hole (202) is located in front of the piston (4); The piston (4) divides the interior of the cylinder (2) into a rodless chamber (203) and a rod chamber (204); the push rod (5) and the rod chamber (204) are both located on the same side of the piston (4); the rodless chamber (203) is connected to a first exhaust hole (1301); when the control valve (9) is in the second state, the valve core (8) moves away from the cylinder (2) and blocks the first exhaust hole (1301); when the control valve (9) is in the first state, the valve core (8) moves toward the cylinder (2) and the first exhaust hole (1301) is connected.

7. The needleless injector according to claim 6, characterized in that: The cross-sectional area of the reset air outlet hole (202) is greater than the cross-sectional area of the reset air inlet hole (201).

8. The needleless injector according to claim 6, wherein: The valve core (8) is penetrated by a connecting hole (801), the rodless chamber (203) is connected to the first exhaust hole (1301) through the connecting hole (801), and an extension portion (401) protrudes from the rear end of the piston (4), the extension portion (401) extends into the connecting hole (801), and a gap is formed between the extension portion (401) and the connecting hole (801).

9. The needleless injector according to claim 6, wherein: The rear end of the valve core (8) protrudes with an annular sealing section (802) for blocking or opening the first exhaust hole (1301); When the control valve (9) is in the first state, the valve core (8) abuts against the end of the cylinder barrel (2), and the sealing section (802) of the valve core (8) opens the first exhaust hole (1301); When the control valve (9) is in the second state, the valve core (8) is away from the cylinder barrel (2), and the sealing section (802) of the valve core (8) blocks the first exhaust hole (1301).

10. The needleless injector according to claim 6, wherein: An end of the control chamber (7) away from the valve core (8) is provided with a second sealing gasket (15) for abutting against the rear end of the sealing section (802) of the valve core (8).

11. The needleless injector according to claim 9, wherein: The first elastic element (10) is located in the sealing section (802), with one end of the first elastic element (10) abutting against the valve core (8) and the other end abutting against the end cover (13).

12. The needleless injector according to claim 1, wherein: The first elastic element (10) is a spring.

13. The needleless injector according to claim 1, wherein: The interior of the cylinder (2) is connected to a second exhaust hole (102), and the second exhaust hole (102) and the push rod (5) are located on the same side of the piston (4).

14. The needleless injector according to claim 1, wherein: The control valve (9) comprises a valve stem (901), a valve seat (903) and a valve body (902); the valve body (902) is fixed on a housing (1); the valve seat (903) is installed in the valve body (902); the valve seat (903) has a valve cavity (9031) and a control hole (9032); the valve body (902) has a valve stem hole (9021), an inlet (9022) and an outlet (9023); The valve cavity (9031) is connected to the inlet (9022) of the valve body (902) through the control hole (9032), and the valve cavity (9031) is connected to the outlet (9023) of the valve body (902). The valve stem (901) is movably installed in the valve stem hole (9021), and the valve body (902) has an exhaust gap (9024). The inner end of the valve stem (901) is fixed with a blocking portion (9011); When the valve stem (901) approaches the control hole (9032), the blocking portion (9011) blocks the control hole (9032), and the outlet (9023) of the valve body (902) communicates with the exhaust gap (9024); when the valve stem (901) moves away from the control hole (9032), the blocking portion (9011) blocks the exhaust gap (9024), and the inlet (9022) of the valve body (902) communicates with the outlet (9023) of the valve body (902) through the control hole (9032). The inlet (9022) of the valve body (902) and the outlet (9023) of the valve body (902) are connected in series on the connecting flow path (11).

15. The needleless injector according to claim 14, wherein: A trigger (904) is hinged on the housing (1), and the trigger (904) is arranged opposite to the outer end of the valve body (902).

16. The needleless injector according to claim 15, characterized in that: A second elastic element (905) is arranged between the trigger (904) and the valve body (902). One end of the second elastic element (905) abuts against the trigger (904), and the other end abuts against the valve body (902).

17. The needleless injector according to claim 14, wherein: The exhaust gap (9024) is formed between the outer peripheral surface of the valve stem (901) and the inner peripheral surface of the valve stem hole (9021).

18. The needleless injector according to claim 1, wherein: The control valve (9) is a manual two-way three-way valve, an electric two-way three-way valve or a pneumatic two-way three-way valve.

19. The needleless injector according to claim 1, wherein: A buckle (16) is fixedly connected to the piston (4). The rear end of the push rod (5) has a flange (501). The buckle (16) has a channel (1601) matching the flange (501). The front end of the buckle (16) has a mounting hole (1602) for the push rod (5) to pass through. The mounting hole (1602) communicates with the channel (1601), and a step surface (1603) is formed between the mounting hole (1602) and the channel (1601). A first notch (1604) is opened above the mounting hole (1602), and a second notch (1605) is opened at the front end of the channel (1601). The first notch (1604) and the second notch (1605) communicate with each other. The push rod (5) is located in the mounting hole (1602), the flange (501) is located in the channel (1601), and the front end face of the flange (501) is opposite to the step surface (1603).

20. The needleless injector according to claim 19, characterized in that: The front end of the buckle (16) has a guiding surface (1606) for guiding the flange (501) into the channel (1601), and the guiding surface (1606) is inclined inward from front to back.

21. The needleless injector according to claim 1, wherein: The barrel assembly (3) includes a barrel (301) and a locking nut (302). One end of the push rod (5) away from the piston (4) is slidably installed in the barrel (301). The rear end of the outer peripheral surface of the barrel (301) has a protruding portion (3011). The locking nut (302) is sleeved outside the barrel (301). One end of the locking nut (302) away from the housing (1) has a bottom edge (3021). The protruding portion (3011) has a limiting structure (303). The rear end of the barrel (301) is inserted into the connection section (103) at the front end of the housing (1). The locking nut (302) is threadedly connected to the housing (1), and the bottom edge (3021) of the locking nut (302) abuts against the limiting structure (303) on the protruding portion (3011). The front end face of the connection section (103) abuts against the rear end face of the protruding portion (3011).

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