Pipeline shut-off valve

Abstract

This invention provides a pipeline shut-off valve, comprising a valve body and a valve core. An inlet and an outlet are respectively located at both ends of the valve body. A valve seat is provided within the valve cavity. A drive unit is located at the front end of the valve core. The drive unit drives the valve core to move linearly relative to the valve seat, closing or opening the valve port between the inlet and outlet. A diaphragm forms a sealing structure between the valve core and the valve seat. When the drive unit drives the valve core to move, the diaphragm flips to adapt to the relative movement between the two. The diaphragm forming the sealing structure between the valve core and the valve seat ensures a reliable sealing effect during the valve core's movement relative to the valve seat. The diaphragm does not rub against the valve core or valve seat, resulting in no wear. The valve port is opened and closed pneumatically, providing rapid response and ensuring quick pipeline connection and disconnection. The entire drive unit is located inside the pipeline shut-off valve, resulting in a small valve size, which is beneficial for pipeline layout.

Description

Technical Field

[0001] This invention relates to the field of liquid transport pipeline technology, and specifically to a pipeline shut-off valve. Background Technology

[0002] Aircraft refueling trucks are the most widely used refueling equipment at large and medium-sized airports, playing a vital role in ensuring aircraft refueling. Aircraft refueling trucks require shut-off valves installed on their fuel delivery pipelines to control fuel supply and shut-off. To achieve rapid on / off switching, intelligent refueling systems on aircraft refueling trucks need to use pneumatically controlled valves instead of manual valves. The most common pneumatically controlled valve is the pneumatic ball valve. However, if a pneumatic ball valve is directly applied to an aircraft refueling truck, its structural characteristics necessitate the installation of a pneumatic actuator. Furthermore, the actuator's valve stem protrudes outside the valve body, resulting in a large overall shut-off valve size, which is inconvenient for pipeline layout. Summary of the Invention

[0003] The purpose of this invention is to provide a pipeline shut-off valve that is small in size and has a long service life.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a pipeline shut-off valve, comprising a valve body and a valve core, with an inlet and an outlet respectively located at both ends of the valve body, a valve seat provided in the valve cavity, and a drive unit provided at the front end of the valve core. The drive unit drives the valve core to move linearly relative to the valve seat to close or open the valve port between the inlet and the outlet. A diaphragm is provided between the valve core and the valve seat to form a sealing structure. When the drive unit drives the valve core to move, the diaphragm flips to adapt to the relative movement between the two.

[0005] The diaphragm is generally shallow and disc-shaped with a Z-shaped cross-section, including an outer lip, an inner lip, and a flipped lip between them. The connection between the outer lip and the flipped lip is rounded, and the connection between the inner lip and the flipped lip is also rounded.

[0006] The radius of the rounded corner at the connection between the outer lip and the flipped lip is 1mm to 2mm, and the radius of the rounded corner at the connection between the inner lip and the flipped lip is 1mm to 2mm.

[0007] The outer ring lip is fixed to the near-end stepped surface of the valve core by a pressure ring and bolts / pins. The inner ring lip is sandwiched between the valve seat and the valve body to form a fixed connection. The outer ring lip and the inner ring lip are arranged in parallel. When the valve core is in the closed and open valve positions, the outer ring lip is located on both sides of the axial direction of the inner ring lip.

[0008] A mounting base is provided on the side of the valve body cavity near the liquid outlet. An inclined surface is provided on the mounting base, and a sealing ring is sandwiched in the middle of the inclined surface. The sealing ring abuts against or separates from the conical surface at the rear end of the valve core to close or open the valve port between the liquid inlet and the liquid outlet.

[0009] The sealing ring has an irregular cross-section, and the mounting base consists of two parts. The sealing ring is sandwiched between the two parts, and the sealing lip of the sealing ring protrudes outside the inclined surface.

[0010] The sealing ring and the mounting base are two separate parts with protruding ribs on their sides. The sealing lip of the sealing ring protrudes outside the inclined surface and has a V-shaped cross section. When the sealing lip abuts against the conical surface at the rear end of the valve core, it forms a line contact sealing fit.

[0011] The drive unit includes a valve stem parallel to the valve body axis. One end of the valve stem is fixed to the valve core, and the other end protrudes into the inner cavity of the valve seat and moves axially with the valve seat. The inner cavity of the valve seat and the inner cavity of the valve body are connected to form a receiving cavity. A compression spring is provided in the receiving cavity. The compression spring provides elastic force to drive the valve stem to drive the valve core to close the valve port. An air inlet is provided on the valve seat. One end of the air inlet communicates with the receiving cavity, and the other end extends outward to the outside of the valve body and communicates with the air source. Compressed air enters the receiving cavity from the air inlet, overcomes the elastic force of the compression spring and the liquid pressure, and drives the valve stem to drive the valve core to open the valve port.

[0012] A guide seat is fitted on the valve stem, and a through hole is opened on the guide seat for the valve stem to pass through. The valve stem and the guide seat form a fixed and sealed fit. One end of the compression spring abuts against the guide seat, and the other end abuts against the inner wall of the valve body that forms the receiving cavity. The outer wall of the guide seat and the inner wall of the receiving cavity form a guiding and sealing fit.

[0013] When the valve is closed, the air intake outlet and the compression spring are located on both sides of the guide seat. An exhaust passage is also provided on the valve body. One end of the exhaust passage is connected to the receiving cavity, and the other end extends outward to the outside of the valve body. When the valve is open, the exhaust outlet and the compression spring are located on the same side of the guide seat. The air intake and exhaust passage are always located on both sides of the guide seat.

[0014] The guide seat is cylindrical in shape and has an annular cavity with an opening facing the compression spring. The inner and outer diameters of the annular cavity match the inner and outer diameters of the compression spring. The end of the compression spring abuts against the bottom wall of the annular cavity. The valve body also has a groove that matches the other end of the compression spring.

[0015] A stepped hole is provided on the inner wall of the valve seat, and a guide sleeve is provided in the stepped hole. An annular groove is provided on the outer wall of the guide seat corresponding to the guide sleeve, and a sealing ring is provided in the annular groove. The air inlet outlet is located on the inner wall of the valve seat on the side of the guide sleeve near the liquid outlet.

[0016] A cone protrudes from the side of the valve seat facing the outlet. A through hole is provided on the cone along its axial direction for the valve stem to pass through. A sealing sleeve is also provided in the through hole.

[0017] The valve stem has two sealing sleeves spaced axially. The sealing sleeves are fitted into an annular groove on the cone. The cross-section of the sealing sleeve is “︹” shaped and the openings of the two sealing sleeves are arranged opposite to each other.

[0018] The above-mentioned solution has at least the following beneficial effects:

[0019] 1. A diaphragm is provided between the valve core and the valve seat to form a sealing structure. The valve core can still maintain a reliable sealing effect relative to the valve seat during the movement of the diaphragm.

[0020] 2. The diaphragm will not rub against the valve core or valve seat, resulting in no wear and ensuring the service life of the entire pipeline shut-off valve;

[0021] 3. The valve is opened and closed pneumatically, with a rapid response, ensuring quick connection and disconnection of the pipeline;

[0022] 4. The entire drive unit is located inside the pipeline stop valve, which is small in size and facilitates pipeline layout. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the pipeline shut-off valve in the closed state.

[0024] Figure 2 This is a schematic diagram of the overall structure of the pipeline shut-off valve in the open state.

[0025] Figure 3 , Figure 4 This is a cross-sectional view of the pipeline shut-off valve in the closed state.

[0026] Figure 5 , Figure 6 This is a cross-sectional view of the pipeline shut-off valve in the open state.

[0027] Figure 7 This is a schematic diagram of the diaphragm in the closed state.

[0028] Figure 8 This is a schematic diagram of the diaphragm in the open state. Implementation

[0029] To facilitate explanation, let's first define the orientation: "front" and "upstream" refer to the side closest to the inlet, while "rear" and "downstream" refer to the side closest to the outlet. The following will combine... Figures 1-8 The present invention will be described in further detail below.

[0030] A pipeline shut-off valve includes a valve body 10 and a valve core 20. An inlet 11 and an outlet 12 are respectively located at both ends of the valve body 10. A valve seat 30 is provided in the valve cavity A. A drive unit 40 is provided at the front end of the valve core 20. The drive unit 40 drives the valve core 20 to move linearly relative to the valve seat 30 to close or open the valve port 15 between the inlet 11 and the outlet 12. A diaphragm 50 is provided between the valve core 20 and the valve seat 30 to form a sealing structure. When the drive unit 40 drives the valve core 20 to move, the diaphragm 50 flips to adapt to the relative movement between the two.

[0031] The working process of the pipeline shut-off valve is as follows: The pipeline shut-off valve is installed in the middle of the pipeline to shut off and guide the liquid in the pipeline. Under normal circumstances, the valve core 20 presses the valve body 10 under the driving force of the drive unit 40 and the pressure of the liquid. The valve port 15 between the inlet port 11 and the outlet port 12 is closed, and the liquid cannot pass through the valve port 15, thus achieving the purpose of shutting off the pipeline. The drive unit 40 provides power to drive the valve core 20 to move linearly relative to the valve seat 30 and leave the valve body 10. At this time, the valve port 15 between the inlet port 11 and the outlet port 12 is opened, and the liquid enters from the inlet port 11 and flows out from the outlet port 12.

[0032] Since the valve seat 30 is fixed relative to the valve body 10, while the valve core 20 is movable and moves linearly relative to the valve seat 30, a diaphragm 50 is provided between the valve core 20 and the valve seat 30 to prevent liquid from passing through the gap between them. This diaphragm 50 forms a sealing structure. The diaphragm 50's flipping action ensures a reliable sealing effect even when the valve core 20 is moving relative to the valve seat 30. Furthermore, the diaphragm 50 does not rub against the valve core 20 or the valve seat 30, resulting in no wear and ensuring the service life of the entire pipeline shut-off valve.

[0033] In a preferred embodiment of the present invention, the diaphragm 50 is generally shallow disc-shaped with a Z-shaped cross-section, including an outer lip 51, an inner lip 52, and a flipping lip 53 between them. The connection between the outer lip 51 and the flipping lip 53 is rounded, as is the connection between the inner lip 52 and the flipping lip 53. The rounded corners ensure the smoothness of the diaphragm 50's flipping action and prevent stress concentration and cracking of the diaphragm 50.

[0034] Extensive testing has shown that the radius of the fillet at the connection between the outer lip 51 and the flip lip 53 is 1mm to 2mm, and the radius of the fillet at the connection between the inner lip 52 and the flip lip 53 is 1mm to 2mm. Under these conditions, the sealing effect and service life of the diaphragm 50 can reach their optimal state simultaneously.

[0035] The outer ring lip 51 is fixed to the near-end stepped surface of the valve core 20 by a pressure ring and bolts / pins. The inner ring lip 52 is sandwiched between the valve seat 30 and the valve body 10 to form a fixed connection. The outer ring lip 51 and the inner ring lip 52 are arranged in parallel. When the valve core 20 is in the closed and open valve port 15 positions, the outer ring lip 51 is located on both sides of the axial direction of the inner ring lip 52. Figure 7 , Figure 8 As shown, the inner ring lip 52 has multiple mounting holes 521 spaced apart along its circumference. Bolts pass through the mounting holes 521 to fix the inner ring lip 52 to the valve body 10. The outer ring lip 51 is fixed to the valve core 20 by pressure rings and bolts / pins, and the fixation is reliable.

[0036] To ensure the sealing of valve port 15 when closed, a sealing ring 14 is provided. To install the sealing ring 14, a mounting base 13 is provided on the side of the inner cavity of valve body 10 near the liquid outlet 12. An inclined surface 131 is provided on the mounting base 13, and the sealing ring 14 is sandwiched in the middle of the inclined surface 131. The sealing ring 14 abuts against or separates from the conical surface 21 at the rear end of valve core 20 to close or open the valve port 15 between the liquid inlet 11 and the liquid outlet 12.

[0037] To accommodate the sealing ring 14, the sealing ring 14 has an irregular cross-section. The mounting base 13 consists of two separate parts, with the sealing ring 14 sandwiched between the two parts. The sealing lip 141 of the sealing ring 14 protrudes beyond the inclined surface 131. The inclined surface 131 is designed to avoid the conical surface 21, allowing the conical surface 21 to abut against the sealing lip 141.

[0038] The stability of the position of the sealing ring 14 is a basic prerequisite for ensuring the sealing performance of the valve port 15. The two parts of the sealing ring 14 and the mounting base 13 are provided with protruding ribs 142 on their sides. The ribs 142 improve the sealing effect between the two parts of the sealing ring and the mounting base 13, making the sealing ring 14 and the mounting base 13 reliably sealed. The sealing lip 141 of the sealing ring 14 protruding outside the inclined surface 131 has a V-shaped cross section. When the sealing lip 141 abuts against the conical surface 21 at the rear end of the valve core 20, it forms a line contact sealing fit, which has a good sealing effect.

[0039] like Figure 3-Figure 6As shown, the drive unit 40 includes a valve stem 41 parallel to the axis of the valve body 10. One end of the valve stem 41 is fixed to the valve core 20, and the other end protrudes into the inner cavity of the valve seat 30 and moves axially with the valve seat 30. The inner cavity of the valve seat 30 and the inner cavity of the valve body 10 are connected to form a receiving cavity B. A compression spring 42 is provided in the receiving cavity B. The compression spring 42 provides elastic force to drive the valve stem 41 to drive the valve core 20 to close the valve port 15. An air inlet a is provided on the valve seat 30. One end of the air inlet a communicates with the receiving cavity B, and the other end extends outward to the outside of the valve body 10 and communicates with the air source. Compressed air enters the receiving cavity B from the air inlet a, overcomes the elastic force of the compression spring 42 and the liquid pressure, and drives the valve stem 41 to drive the valve core 20 to open the valve port 15. In its natural state, the elastic force of the compression spring 42 and the pressure of the liquid jointly drive the valve stem 41 to move to the left as shown in the figure. The valve stem 41 drives the valve core 20 to move to the left, causing its conical surface 21 to abut against the sealing lip 141, thereby sealing the valve port 15 and blocking the flow passage. Compressed gas is introduced into the air inlet a. The compressed gas enters the receiving cavity B from the air inlet a, overcoming the elastic force of the compression spring 42 and the liquid pressure, and drives the valve stem 41 to drive the valve core 20 to open the valve port 15, with a rapid response. Most importantly, the entire drive unit 40 is located inside the pipeline shut-off valve, making the entire pipeline shut-off valve small in size, which is beneficial for pipeline layout.

[0040] To ensure that the valve stem 41 can drive the valve core 20 to move linearly along the axis of the valve body, a guide seat 43 is fitted on the valve stem 41. The guide seat 43 has a through hole for the valve stem 41 to pass through. The valve stem 41 and the guide seat 43 form a fixed and sealed fit. One end of the compression spring 42 abuts against the guide seat 43, and the other end abuts against the inner wall of the valve body 10 that forms the receiving cavity B. The outer wall of the guide seat 43 and the inner wall of the receiving cavity B form a guiding and sealing fit. By forming a guiding and sealing fit between the guide seat 43 and the inner wall of the receiving cavity B, the linear movement of the valve stem 41 and the valve core 20 can be ensured to be smooth. On the other hand, the leakage of compressed gas in the receiving cavity B can be avoided, thus improving the timeliness of opening the valve port 15.

[0041] With valve port 15 closed, the air intake a outlet and the compression spring 42 are located on both sides of the guide seat 43. Because with valve port 15 closed, the guide seat 43 is located at the leftmost position of the receiving cavity B. At this time, the air intake a outlet and the compression spring 42 are located on both sides of the guide seat 43. Therefore, in any state, it can be ensured that the air intake a outlet and the compression spring 42 are located on both sides of the guide seat 43. When compressed air is introduced into the receiving cavity B, the compressed air can drive the guide seat 43 to overcome the elastic force of the compression spring 42 and move to the right as shown in the figure, ensuring that valve port 15 is in the open state. The valve body 10 is also provided with an exhaust passage b. One end of the exhaust passage b communicates with the receiving cavity B, and the other end extends outward to the outside of the valve body 10. When the valve port 15 is open, the outlet of the exhaust passage b and the compression spring 42 are located on the same side of the guide seat 43. Because when the valve port 15 is open, the guide seat 43 is located at the rightmost position of the receiving cavity B. At this time, the outlet of the exhaust passage b and the compression spring 42 are located on the same side of the guide seat 43. Therefore, regardless of the state, the outlet of the exhaust passage b and the compression spring 42 are always located on the same side of the guide seat 43, thereby venting air from the right side. The intake passage a and the exhaust passage b are always located on both sides of the guide seat 43, one for intake and one for exhaust, cooperating with each other.

[0042] Specifically, the guide seat 43 is cylindrical in shape and has an annular cavity 431 with an opening facing the compression spring 42. The inner and outer diameters of the annular cavity 431 match the inner and outer diameters of the compression spring 42. This not only limits the position of the compression spring 42 but also guides its movement. The end of the compression spring 42 abuts against the bottom wall of the annular cavity 431. The valve body 10 also has a groove 16 that mates with the other end of the compression spring 42.

[0043] Furthermore, a stepped hole is formed on the inner wall of the valve seat 30, and a guide sleeve 36 is installed in the stepped hole. An annular groove 432 is formed on the outer wall of the guide seat 43 corresponding to the guide sleeve 36, and a sealing ring 433 is installed in the annular groove 432. The air inlet a outlet is located on the inner wall of the valve seat 30 on the side of the guide sleeve 36 near the liquid outlet. The guide sleeve 36 is usually made of copper, which is wear-resistant and can improve the service life of the entire pipeline shut-off valve; at the same time, it can ensure the smooth linear movement of the guide seat 43.

[0044] A cone 33 protrudes from the valve seat 30 towards the outlet 12. A through hole for the valve stem 41 to pass through is formed along the axial direction of the cone 33, and a sealing sleeve 34 is also installed inside the through hole. When the valve port 15 is open, the rear end of the cone 33 abuts against the valve core 20, limiting the valve core 20's movement and preventing excessive stroke that could damage the diaphragm 50. Buffer pads or other components can also be installed on the contact surfaces to extend service life and reduce noise.

[0045] To prevent liquid from entering the receiving cavity B, two sealing sleeves 34 are axially spaced on the valve stem 41. Each sealing sleeve 34 is fitted into an annular groove 35 on the cone 33. The cross-section of the sealing sleeve 34 is shaped like a "︹", and the openings of the two sealing sleeves 34 are arranged opposite to each other. Thus, the left sealing sleeve 34 deforms under the pressure of the liquid, its opening widens, and it tightly adheres to the valve stem 41 and the annular groove 35, preventing liquid from passing through. Similarly, the right sealing sleeve 34 deforms under the pressure of compressed air in the receiving cavity B, its opening widens, and it tightly adheres to the valve stem 41 and the annular groove 35, preventing gas from passing through. This ensures the sealing performance of the receiving cavity B.

Claims

1. A pipeline shut-off valve, comprising a valve body (10) and a valve core (20), wherein an inlet (11) and an outlet (12) are respectively disposed at both ends of the valve body (10), a valve seat (30) is provided in the valve cavity (A), and a drive unit (40) is provided at the front end of the valve core (20), the drive unit (40) driving the valve core (20) to move linearly relative to the valve seat (30) to close or open the valve port (15) between the inlet (11) and the outlet (12), characterized in that: A diaphragm (50) is provided between the valve core (20) and the valve seat (30) to form a sealing structure. When the drive unit (40) drives the valve core (20) to move, the diaphragm (50) flips to adapt to the relative movement between the two. The drive unit (40) includes a valve stem (41) parallel to the axis of the valve body (10). One end of the valve stem (41) is fixed to the valve core (20), and the other end protrudes into the inner cavity of the valve seat (30) and moves axially with the valve seat (30). The inner cavity of the valve seat (30) and the inner cavity of the valve body (10) are connected to form a receiving cavity (B). A compression spring (42) is provided in the receiving cavity (B). The compression spring (42) provides elastic force to drive the valve stem (41) to drive the valve core (20) to close the valve port (15). An air inlet (a) is provided on the valve seat (30). One end of the air inlet (a) is connected to the receiving cavity (B), and the other end extends outward to the outside of the valve body (10) and is connected to the air source. Compressed air enters the receiving cavity (B) from the air inlet (a), overcomes the elastic force of the compression spring (42) and the liquid pressure, and drives the valve stem (41) to drive the valve core (20) to open the valve port (15). The diaphragm (50) is generally shallow and has a Z-shaped cross section, including an outer lip (51), an inner lip (52), and a flipped lip (53) between them. The connection between the outer lip (51) and the flipped lip (53) is rounded, and the connection between the inner lip (52) and the flipped lip (53) is also rounded.

2. The pipeline shut-off valve according to claim 1, characterized in that: The radius of the rounded corner at the connection between the outer lip (51) and the flipped lip (53) is 1mm to 2mm, and the radius of the rounded corner at the connection between the inner lip (52) and the flipped lip (53) is 1mm to 2mm.

3. The pipeline shut-off valve according to claim 1, characterized in that: The outer ring lip (51) is fixed to the near-end step surface of the valve core (20) by a pressure ring and bolts / pins. The inner ring lip (52) is sandwiched between the valve seat (30) and the valve body (10) to form a fixed connection. The outer ring lip (51) and the inner ring lip (52) are arranged in parallel. When the valve core (20) is in the closed and open valve port (15) positions, the outer ring lip (51) is located on both sides of the axial direction of the inner ring lip (52).

4. The pipeline shut-off valve according to claim 1, characterized in that: A mounting base (13) is provided on the side of the inner cavity of the valve body (10) near the liquid outlet (12). An inclined surface (131) is provided on the mounting base (13). A sealing ring (14) is sandwiched in the middle of the inclined surface (131). The sealing ring (14) abuts against or separates from the conical surface (21) at the rear end of the valve core (20) to close or open the valve port (15) between the liquid inlet (11) and the liquid outlet (12).

5. The pipeline shut-off valve according to claim 4, characterized in that: The mounting base (13) consists of two parts, with the sealing ring (14) sandwiched between the two parts. The sealing lip (141) of the sealing ring (14) protrudes outside the inclined surface (131).

6. The pipeline shut-off valve according to claim 5, characterized in that: The sealing ring (14) and the mounting base (13) are two separate parts with protruding ribs (142) on their sides. The sealing lip (141) of the sealing ring (14) protruding outside the inclined surface (131) has a V-shaped cross section. When the sealing lip (141) abuts against the conical surface (21) at the rear end of the valve core (20), a line contact sealing fit is formed.

7. The pipeline shut-off valve according to claim 1, characterized in that: A guide seat (43) is fitted on the valve stem (41). The guide seat (43) has a through hole for the valve stem (41) to pass through. The valve stem (41) and the guide seat (43) form a fixed and sealed fit. One end of the compression spring (42) abuts against the guide seat (43) and the other end abuts against the inner wall of the valve body (10) that forms the receiving cavity (B). The outer wall of the guide seat (43) and the inner wall of the receiving cavity (B) form a guiding and sealing fit.

8. The pipeline shut-off valve according to claim 1, characterized in that: When the valve port (15) is closed, the outlet of the air intake (a) and the compression spring (42) are located on both sides of the guide seat (43); the valve body (10) is also provided with an exhaust passage (b), one end of which is connected to the receiving cavity (B) and the other end extends outward to the outside of the valve body (10). When the valve port (15) is open, the outlet of the exhaust passage (b) and the compression spring (42) are located on the same side of the guide seat (43), and the air intake (a) and the exhaust passage (b) are always located on both sides of the guide seat (43).

9. The pipeline shut-off valve according to claim 7, characterized in that: The guide seat (43) is cylindrical in shape and has an annular cavity (431) with an opening facing the compression spring (42). The inner and outer diameters of the annular cavity (431) match the inner and outer diameters of the compression spring (42). The end of the compression spring (42) abuts against the bottom wall of the annular cavity (431). The valve body (10) also has a groove (16) that matches the other end of the compression spring (42).

10. The pipeline shut-off valve according to claim 7, characterized in that: A stepped hole is provided on the inner wall of the valve seat (30), and a guide sleeve (36) is provided in the stepped hole. An annular groove (432) is provided on the outer wall of the guide seat (43) corresponding to the guide sleeve (36), and a sealing ring (433) is provided in the annular groove (432). The outlet of the air inlet (a) is located on the inner wall of the valve seat (30) on the side of the guide sleeve (36) near the liquid outlet.

11. The pipeline shut-off valve according to claim 1, characterized in that: A cone (33) is provided on the side of the valve seat (30) facing the liquid outlet (12). A through hole for the valve stem (41) to pass through is provided on the cone (33) along its axial direction. A sealing sleeve (34) is also provided in the through hole.

12. The pipeline shut-off valve according to claim 11, characterized in that: Two sealing sleeves (34) are provided axially at intervals on the valve stem (41). The sealing sleeves (34) are fitted into the annular groove (35) opened on the cone (33). The cross section of the sealing sleeves (34) is in the shape of "︹" and the openings of the two sealing sleeves (34) are arranged opposite to each other.

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