Needle valve mechanism and gas injector

Abstract

The present invention relates to the technical field of gas injectors, and specifically discloses a needle valve mechanism and a gas injector, wherein the needle valve mechanism includes a valve body, a valve needle assembly, and a buffer assembly. The buffer assembly includes a buffer seat and a buffer movable member, which seals the outer wall of the buffer seat with the inner wall of the flow chamber, and the buffer movable member is movably arranged in the buffer chamber, thereby achieving the function of abutting or avoiding the valve needle assembly. The needle valve mechanism of the present invention, by providing a buffer assembly, effectively solves the problem in the prior art that when the valve needle returns to its original position after opening the valve port, it will cause significant impact wear on the contact surface of the valve port, resulting in an increase in the stroke of the valve needle, thereby affecting the stability of the gas injector's injection volume.

Description

Technical Field

[0001] The present invention relates to the technical field of gas injectors, and in particular to a needle valve mechanism and a gas injector. Background Art

[0002] At present, for the types of gas injectors known in the prior art, compared with liquid fuel injectors, gas injectors require a larger stroke, and the contact sealing surface is not lubricated with oil. In the process of returning the valve needle after opening the valve port, dry friction and dry impact will be formed on the contact surface of the valve port, which may cause large impact wear on the sealing contact surface and cause the stroke of the valve needle to increase, thereby affecting the stability and consistency of the gas injector injection volume and affecting the service life of the needle valve mechanism. Summary of the Invention

[0003] The purpose of the present invention is to provide a needle valve mechanism and a gas injector to solve the problem in the prior art that when the valve needle returns to its original position after opening the valve port, it will cause large impact wear on the contact surface of the valve port, causing the valve needle's stroke to increase, thereby affecting the stability of the gas injector's injection volume.

[0004] On the one hand, the present invention provides a needle valve mechanism, which includes: a valve body, having a flow chamber and a valve port that are interconnected, the flow chamber being used for circulating gas fuel; a valve needle assembly, movably arranged in the flow chamber to block or avoid the valve port; a buffer assembly, including a buffer seat and a buffer movable part, the buffer seat being arranged in the flow chamber and located on the side of the valve needle assembly away from the valve port, the outer wall of the buffer seat being sealed with the inner wall of the flow chamber, the buffer seat having a buffer chamber and a first communicating hole, the first communicating hole being connected to the flow chamber, the buffer movable part having a throttling communicating hole, the throttling communicating hole passing through the buffer movable part along the axial direction of the valve needle assembly, the buffer chamber being able to communicate with the flow chamber through the throttling communicating hole, the buffer movable part being movably arranged in the buffer chamber to abut against or avoid the valve needle assembly.

[0005] As an optional technical solution for the needle valve mechanism, the buffer assembly also includes a buffer elastic part, which is located in the buffer cavity. One end of the buffer elastic part abuts against the inner wall of the buffer cavity, and the other end of the buffer elastic part abuts against the end of the buffer movable part away from the valve port.

[0006] As an optional technical solution of the needle valve mechanism, the buffer elastic member is a buffer spring, and the stiffness of the buffer spring is k, 0.5N / mm≤k≤1.5N / mm.

[0007] As an optional technical solution for the needle valve mechanism, the throttling connecting hole includes a first flow hole, a throttling hole and a second flow hole that are connected in sequence, the first flow hole is connected to the flow cavity, the second flow hole is connected to the buffer cavity, and the aperture of the throttling hole is smaller than the aperture of the first flow hole and the aperture of the second flow hole.

[0008] As an optional technical solution of the needle valve mechanism, at least a portion of the buffer movable member is located in the buffer cavity, and a gap between the movable member and the inner wall of the buffer cavity is 0.005 mm-0.0.1 mm.

[0009] As an optional technical solution for the needle valve mechanism, the end face of the buffer movable part facing the valve port abuts against the end face of the valve needle assembly away from the valve port to form a sealing structure. The sealing structure can seal the throttling connecting hole. The sealing structure is a plane seal, a spherical seal, a conical seal or a non-metallic seal.

[0010] As an optional technical solution for the needle valve mechanism, the valve needle assembly includes a valve needle body, a limiter and a return elastic member. The limiter is sleeved on the valve needle body and connected to the inner wall of the circulation cavity. The two ends of the return elastic member respectively abut the limiter and the inner wall of the circulation cavity. The valve needle body is movably arranged in the circulation cavity to block or avoid the valve port, and the valve needle body can abut against the buffer movable member.

[0011] As an optional technical solution for the needle valve mechanism, the limiting member includes a limiting block and a fixed block. The limiting block is sleeved on the valve needle body and connected to the inner wall of the circulation cavity. The fixed block is sleeved on the valve needle body and abuts against one end of the limiting block away from the valve port. The limiting block has a second communicating hole, which connects the circulation cavity with the valve port.

[0012] As an optional technical solution for the needle valve mechanism, the valve needle body includes a first section, a second section and a sealing section connected in sequence, the diameter of the first section is smaller than the diameter of the second section, the diameter of the second section is smaller than the diameter of the sealing section, the first section can abut against the buffer movable part, and the sealing section is located outside the valve body and can block or avoid the valve port.

[0013] In another aspect, the present invention provides a gas injector comprising the needle valve mechanism described in any one of the above solutions.

[0014] The beneficial effects of the present invention are:

[0015] The present invention provides a needle valve mechanism comprising a valve body, a valve needle assembly, and a buffer assembly. The valve body comprises a flow chamber and a valve port, which are interconnected. The buffer assembly comprises a buffer seat and a movable buffer member. The needle valve mechanism of the present invention comprises a buffer seat and a movable buffer member, wherein the outer wall of the buffer seat is sealed against the inner wall of the flow chamber. The movable buffer member is movably disposed within the buffer chamber, thereby abutting or avoiding the valve needle assembly. Among them, after the gas fuel passes through the circulation chamber and the first circulation hole in sequence, the pressure generated by the gas fuel acts on the valve needle assembly, causing the valve needle assembly to open the valve port and the gas injector to start working. At this time, in the process of the valve needle assembly opening the valve port, the buffer movable part will not move toward the valve needle assembly due to the vacuum suction of the buffer chamber. At this time, the buffer movable part avoids the valve needle assembly, and the buffer chamber is connected with the circulation chamber through the throttling connecting hole. The gas fuel enters the buffer chamber. At this time, the buffer movable part moves toward the valve needle assembly due to its own gravity; when the gas fuel is stopped from being introduced, in the process of the valve needle assembly returning to its original position, the valve needle assembly abuts against the buffer movable part. Due to the action of the throttling connecting hole, the valve needle assembly is prevented from separating from the buffer movable part, so that the buffer movable part can play a buffering role on the valve needle assembly when returning, effectively preventing the valve needle assembly from colliding with and wearing the valve port. By utilizing the needle valve mechanism of the present invention and providing a buffer assembly, the problem in the prior art that when the valve needle returns to its original position after opening the valve port, the contact surface of the valve port will suffer significant impact wear, which will increase the stroke of the valve needle and affect the stability of the gas injector's jet volume is effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a cross-sectional view of a needle valve mechanism in an embodiment of the present invention;

[0017] Figure 2 for Figure 1 A partial enlarged view of the .

[0018] In the picture:

[0019] 1. Valve body; 11. Flow chamber; 12. Valve port; 13. First step surface; 14. Second step surface;

[0020] 2. Valve needle assembly; 21. Valve needle body; 211. First section; 212. Second section; 213. Blocking section; 2131. Abutting surface; 22. Positioning member; 221. Positioning block; 2211. Second communicating hole; 222. Fixing block; 23. Return elastic member;

[0021] 3. Buffer assembly; 31. Buffer seat; 311. Buffer cavity; 312. First communication hole; 32. Buffer movable member; 321. Throttling communication hole; 3211. First flow hole; 3212. Throttling hole; 3213. Second flow hole; 33. Buffer elastic member;

[0022] 4. Sealing structure. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0024] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature being "above", "above" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0025] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0026] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0027] like Figures 1 to 2As shown, this embodiment provides a needle valve mechanism, which includes a valve body 1, a valve needle assembly 2 and a buffer assembly 3. Among them, the valve body 1 has a circulation chamber 11 and a valve port 12 that are interconnected, and the circulation chamber 11 is used for the circulation of gas fuel; the valve needle assembly 2 is movably arranged in the circulation chamber 11 to block or avoid the valve port 12; the buffer assembly 3 includes a buffer seat 31 and a buffer movable part 32, the buffer seat 31 is arranged in the circulation chamber 11, and is located on the side of the valve needle assembly 2 away from the valve port 12, the outer wall of the buffer seat 31 is sealed with the inner wall of the circulation chamber 11, the buffer seat 31 has a buffer chamber 311 and a first connecting hole 312, the first connecting hole 312 is connected to the circulation chamber 11, the buffer movable part 32 has a throttling connecting hole 321, the throttling connecting hole 321 passes through the buffer movable part 32 along the axial direction of the valve needle assembly 2, the buffer chamber 311 can be connected with the circulation chamber 11 through the throttling connecting hole 321, the buffer movable part 32 is movably arranged in the buffer chamber 311 to abut or avoid the valve needle assembly 2.

[0028] When the gas fuel passes through the circulation chamber 11 and the first connecting hole 312 in sequence, the pressure generated by the gas fuel acts on the valve needle assembly 2, causing the valve needle assembly 2 to open the valve port 12, and the gas injector starts to work. At this time, in the process of the valve needle assembly 2 opening the valve port 12, the buffer movable part 32 will not move toward the valve needle assembly 2 due to the vacuum suction of the buffer chamber 311. At this time, the buffer movable part 32 avoids the valve needle assembly 2, and the buffer chamber 311 is connected with the circulation chamber 11 through the throttling connecting hole 321. The gas fuel enters the buffer chamber 311. At this time, the buffer movable part 32 moves toward the valve needle assembly 2 due to its own gravity; when the gas fuel is stopped from being introduced, in the process of the valve needle assembly 2 returning to its original position, the valve needle assembly 2 abuts against the buffer movable part 32. Due to the action of the throttling connecting hole 321, the valve needle assembly 2 is prevented from separating from the buffer movable part 32, so that the buffer movable part 32 can play a buffering role on the valve needle assembly 2 when returning, effectively preventing the valve needle assembly 2 from colliding and wearing the valve port 12. By utilizing the needle valve mechanism of the present invention and providing a buffer assembly 3, the problem in the prior art that when the valve needle returns to its original position after opening the valve port, the contact surface of the valve port will be severely impacted and worn, resulting in an increase in the stroke of the valve needle and affecting the stability of the gas injector's jet volume is effectively solved.

[0029] It should be noted that the buffer chamber designed in the present invention has a fixed sealed volume. The pneumatic damping generated during the movement can resist the rebound force generated by the return elastic part of the valve needle assembly 2, slow down the return speed of the valve needle assembly 2, thereby reducing the impact force of the contact surface between the valve needle assembly 2 and the valve port 12, reducing the rebound and seating impact, thereby reducing impact wear, controlling the stroke amount, and improving the service life of the needle valve mechanism.

[0030] Among them, the return and rebound of the valve needle assembly 2 are directly buffered by using a fixed sealed volume to generate air resistance. At the same time, the size of the buffer chamber and the throttling connecting hole 321 needs to be accurately calculated and determined, and the weight of the buffer movable part needs to be designed to be greater than the air resistance so that the return response of the buffer movable part meets the design requirements.

[0031] In some embodiments, the buffer assembly 3 further includes a buffering elastic member 33. The buffering elastic member 33 is positioned within the buffer cavity 311, with one end of the buffering elastic member 33 abutting the inner wall of the buffer cavity 311, and the other end of the buffering elastic member 33 abutting the end of the buffering movable member 32 facing away from the valve port 12. This arrangement propels the buffering movable member 32, effectively increasing the speed of its return response. The buffering elastic member 33 has a certain degree of compression.

[0032] Specifically, in this embodiment, the buffer elastic member 33 is a buffer spring, wherein the stiffness of the buffer spring is k, 0.5 N / mm ≤ k ≤ 1.5 N / mm. This configuration preferably uses a low-stiffness spring to prevent significant compression that could affect the movement of the buffer movable member 32. The buffer spring stiffness can be adjusted based on the design weight of the buffer movable member 32.

[0033] Optionally, the buffer movable member 32 is a buffer piston, the buffer piston has a spring fixing groove, and the other end of the buffer spring is arranged in the spring fixing groove.

[0034] like Figure 2 As shown, the throttle communication hole 321 includes a first flow hole 3211, a throttle hole 3212, and a second flow hole 3213, which are connected in sequence. The first flow hole 3211 is connected to the flow chamber 11, and the second flow hole 3213 is connected to the buffer chamber 311. The aperture of the throttle hole 3212 is set to be smaller than the apertures of the first flow hole 3211 and the second flow hole 3213. The aperture size of the throttle hole 3212 is adjustable, so that the falling speed of the buffer piston can be controlled according to the size of the throttle hole 3212 and the stiffness of the buffer spring. At the same time, the parameter design of the throttle hole 3212 needs to take into account the injection time and interval of the gas injector.

[0035] Among them, the aperture size of the throttle hole 3212 needs to be calculated according to the volume of the buffer chamber 311, and the flow rate of the throttle hole 3212 and the volume of the buffer chamber 311 need to have a certain ratio. During the downward process of the valve needle assembly 2, it can ensure that the throttle hole 3212 can quickly balance the pressure difference between the inside and outside of the buffer chamber 311 to improve the responsiveness of the buffer piston movement, and during the upward process of the valve needle assembly 2, it can ensure that the throttle hole 3212 can produce a throttling effect to prevent the valve needle assembly 2 from separating from the buffer piston, so as to control the magnitude of the buffer force.

[0036] Furthermore, at least a portion of the buffer movable member 32 is located within the buffer cavity 311, and a gap of 0.005 mm to 0.0.1 mm is maintained between the buffer movable member 32 and the inner wall of the buffer cavity 311. This arrangement ensures that the buffer movable member 32 can move smoothly within the buffer cavity 311 while preventing excessive gas from entering the buffer cavity 311 through the gap between the buffer movable member 32 and the inner wall of the buffer cavity 311.

[0037] Specifically, the end surface of the buffer movable member 32 facing the valve port 12 abuts against the end surface of the valve needle assembly 2 facing away from the valve port 12 to form a sealing structure 4. The sealing structure 4 can seal the throttling communication hole 321. In some embodiments, the sealing structure 4 can be configured as a flat seal, a spherical seal, a conical seal, or a non-metallic seal.

[0038] Among them, the sealing contact surface of the plane seal is a plane, and the sealing effect is achieved through uniformly distributed sealing pressure.

[0039] The conical sealing surface of a spherical seal creates a high sealing pressure ratio under axial force through a narrow contact surface. A guide structure (such as a disc guide) is usually required to ensure precise alignment of the sealing surface.

[0040] The sealing contact surface of the conical seal is a spherical surface, which relies on the line contact or narrow surface contact between the ball and the valve seat to form a high specific pressure seal.

[0041] Non-metallic seals are made of non-metallic materials such as rubber, plastic (e.g., fluororubber, silicone rubber), and graphite, achieving sealing through elastic deformation and filling microscopic gaps. Some metal-non-metal composite structures enhance performance. In this embodiment, this reduces friction between the movable buffer member 32 and the valve needle assembly 2 during contact, thereby increasing service life.

[0042] Specifically, the valve needle assembly 2 includes a valve needle body 21, a stopper 22, and a return elastic member 23. The stopper 22 is sleeved onto the valve needle body 21 and connected to the inner wall of the circulation chamber 11. The stopper 22 can limit the position of the valve needle body 21, thereby restricting the range of movement of the valve needle body 21. The two ends of the return elastic member 23 respectively abut the stopper 22 and the inner wall of the circulation chamber 11. In this arrangement, the return elastic member 23 can return the valve needle body 21. The valve needle body 21 is movably arranged in the circulation chamber 11 to block or avoid the valve port 12. The valve needle body 21 can abut against the buffer movable member 32.

[0043] Furthermore, the limiting member 22 includes a limiting block 221 and a fixing block 222. The limiting block 221 is sleeved onto the valve needle body 21 and connected to the inner wall of the flow chamber 11. The fixing block 222 is sleeved onto the valve needle body 21 and abuts against the end of the limiting block 221 facing away from the valve port 12 to secure the limiting block 221. The limiting block 221 has a second connecting hole 2211, which connects the flow chamber 11 with the valve port 12, so that the gas fuel can be ejected from the valve port 12 after passing through the second connecting hole 2211.

[0044] Alternatively, as Figure 1 As shown, the valve body has a first step surface 13 and a second step surface, the distance between the limit block 221 and the first step surface 13 is H, H is the maximum movement range of the valve needle body 21, and the two ends of one end of the return elastic member 23 respectively abut the limit block 221 and the second step surface 14.

[0045] Specifically, the valve needle body 21 includes a first section 211, a second section 212, and a blocking section 213, which are sequentially connected. The diameter of the first section 211 is smaller than that of the second section 212, which in turn is smaller than that of the blocking section 213. The first section 211 abuts against the movable buffer member 32. The blocking section 213 is located outside the valve body 1 and can block or avoid the valve port 12. The blocking section has an abutting surface 2131, which blocks or avoids the valve port 12.

[0046] This embodiment also provides a gas injector, comprising the needle valve mechanism in the above solution. When the gas fuel passes through the circulation chamber 11 and the first connecting hole 312 in sequence, the pressure generated by the gas fuel acts on the valve needle assembly 2, causing the valve needle assembly 2 to open the valve port 12, and the gas injector starts to work. At this time, in the process of the valve needle assembly 2 opening the valve port 12, the buffer movable part 32 will not move toward the valve needle assembly 2 due to the vacuum suction of the buffer chamber 311. At this time, the buffer movable part 32 avoids the valve needle assembly 2, and the buffer chamber 311 is connected with the circulation chamber 11 through the throttling connecting hole 321. The gas fuel enters the buffer chamber 311. At this time, the buffer movable part 32 moves toward the valve needle assembly 2 due to its own gravity; when the gas fuel is stopped from being introduced, in the process of the valve needle assembly 2 returning to its original position, the valve needle assembly 2 abuts against the buffer movable part 32. Due to the action of the throttling connecting hole 321, the valve needle assembly 2 is prevented from separating from the buffer movable part 32, so that the buffer movable part 32 can play a buffering role on the valve needle assembly 2 when returning, effectively preventing the valve needle assembly 2 from colliding and wearing the valve port 12. By using the gas injector of the present invention, by providing a buffer component 3, the problem in the prior art that when the valve needle returns to its original position after opening the valve port, the contact surface of the valve port will suffer severe impact wear, resulting in an increase in the stroke of the valve needle, thereby affecting the stability of the gas injector's jet volume is effectively solved.

[0047] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A needle valve mechanism, which can be used in a gas injector, characterized in that: include: A valve body (1) having a flow cavity (11) and a valve port (12) that are interconnected, wherein the flow cavity (11) is used for allowing gas fuel to flow; A valve needle assembly (2) is movably arranged in the circulation cavity (11) to block or avoid the valve port (12); A buffer assembly (3) includes a buffer seat (31) and a buffer movable member (32), wherein the buffer seat (31) is arranged in the circulation cavity (11) and is located on the side of the valve needle assembly (2) away from the valve port (12), the outer wall of the buffer seat (31) is sealed with the inner wall of the circulation cavity (11), the buffer seat (31) has a buffer cavity (311) and a first communicating hole (312), the first communicating hole (312) is connected to the circulation cavity (11), and the buffer The movable member (32) has a throttling communication hole (321), the throttling communication hole (321) penetrates the buffer movable member (32) along the axial direction of the valve needle assembly (2), the buffer cavity (311) can be communicated with the flow cavity (11) through the throttling communication hole (321), and the buffer movable member (32) is movably arranged in the buffer cavity (311) to abut against or avoid the valve needle assembly (2); the weight of the buffer movable member (32) is designed to be greater than the air resistance; The throttling communication hole (321) comprises a first circulation hole (3211), a throttling hole (3212), and a second circulation hole (3213) which are sequentially connected from bottom to top, the first circulation hole (3211) being connected to the circulation cavity (11), the second circulation hole (3213) being connected to the buffer cavity (311), and the aperture of the throttling hole (3212) being smaller than the apertures of the first circulation hole (3211) and the second circulation hole (3213); At least a portion of the buffer movable part (32) is located in the buffer cavity (311), and a gap between the movable part and the inner wall of the buffer cavity (311) is 0.005 mm.

2. The needle valve mechanism according to claim 1, wherein: The buffer assembly (3) further comprises a buffer elastic member (33), the buffer elastic member (33) being located in the buffer cavity (311), one end of the buffer elastic member (33) being in contact with the inner wall of the buffer cavity (311), and the other end of the buffer elastic member (33) being in contact with an end of the buffer movable member (32) facing away from the valve port (12).

3. The needle valve mechanism according to claim 2, characterized in that: The buffer elastic member (33) is a buffer spring, and the stiffness of the buffer spring is k, 0.5 N / mm≤k≤1.5 N / mm.

4. The needle valve mechanism according to claim 1, wherein: The end face of the buffer movable part (32) facing the valve port (12) abuts against the end face of the valve needle assembly (2) facing away from the valve port (12) to form a sealing structure (4). The sealing structure (4) can seal the throttling communication hole (321). The sealing structure (4) is a plane seal, a spherical seal, a conical seal, or a non-metallic seal.

5. The needle valve mechanism according to claim 1, characterized in that: The valve needle assembly (2) includes a valve needle body (21), a limiting member (22) and a return elastic member (23), wherein the limiting member (22) is sleeved on the valve needle body (21) and connected to the inner wall of the circulation cavity (11), and the two ends of the return elastic member (23) respectively abut the limiting member (22) and the inner wall of the circulation cavity (11), and the valve needle body (21) is movably arranged in the circulation cavity (11) to block or avoid the valve port (12), and the valve needle body (21) can abut against the buffer movable member (32).

6. The needle valve mechanism according to claim 5, characterized in that: The limiting member (22) includes a limiting block (221) and a fixing block (222), wherein the limiting block (221) is sleeved on the valve needle body (21) and connected to the inner wall of the circulation cavity (11), and the fixing block (222) is sleeved on the valve needle body (21) and abuts against an end of the limiting block (221) away from the valve port (12), and the limiting block (221) has a second communicating hole (2211), and the second communicating hole (2211) connects the circulation cavity (11) with the valve port (12).

7. The needle valve mechanism according to claim 5, characterized in that: The valve needle body (21) includes a first section (211), a second section (212) and a blocking section (213) connected in sequence, the diameter of the first section (211) is smaller than the diameter of the second section (212), the diameter of the second section (212) is smaller than the diameter of the blocking section (213), the first section (211) can abut against the buffer movable part (32), and the blocking section (213) is located outside the valve body (1) and can block or avoid the valve port (12).

8. A gas injector, characterized in that: Comprising the needle valve mechanism according to any one of claims 1 to 7.

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