Self-centering high-pressure on-off valve

Abstract

The utility model discloses a self-centering high-pressure on-off valve which is characterized in that an inclined wedge block is connected above a base in a sliding manner, the inclined wedge block is connected with an air cylinder along the sliding direction of the inclined wedge block, a fixed seat is connected above the inclined wedge block in a sliding manner, an air guide rod is arranged above the fixed seat, a first air guide hole which is through up and down is formed in the air guide rod, and an air inlet hole is formed in the fixed seat; the outer side of the air guide rod is connected with a guide rod sleeve in a sliding fit mode, the outer side of the guide rod sleeve is sleeved with an upper cover, a channel used for installing the guide rod sleeve is arranged in the upper cover, an air outlet hole is connected to the upper portion of the channel, a floating head is arranged in the channel, a plurality of second air guide holes are formed in the floating head, and a plugging head is arranged in the middle of the lower portion of the floating head. The self-centering floating head has the advantages that the self-centering effect on the floating head is achieved, the sealing performance between the plugging head and the air guide rod and the sealing performance between the floating head and the upper cover can be guaranteed, and internal leakage cannot occur; and the device is not influenced by the effect of high-pressure gas, can quickly and conveniently realize the on-off of conveyed gas, and is easy to control.

Description

TECHNICAL FIELD

[0001] The utility model relates to on-off valve technical field, concretely is a kind of self-centering high-pressure on-off valve. BACKGROUND

[0002] On-off valve is widely used in liquid, gas and steam pipeline lamp system, can improve the safety and operating efficiency of pipeline system. Pneumatic on-off valve is a commonly used control element, for controlling the on-off of gas or liquid fluid medium, is widely used in helium detection equipment. The existing pneumatic on-off valve mostly uses elastic member as the element of valve body on-off, but in the high-pressure gas conveying process, due to high pressure, it is easy to cause the valve to produce internal leakage, affect the sealing performance of valve, and further affect the ability of helium detection equipment. As the on-off valve disclosed in patent publication No. CN117662772A, the on-off valve of 202311719381.4 is used, which realizes the on-off control of valve body by using elastic expansion pipe, but the elastic structure is easy to leak under the action of high-pressure gas. SUMMARY

[0003] The utility model aims at providing a kind of self-centering high-pressure on-off valve to solve the problems raised in the above background.

[0004] To achieve the above object, the utility model provides the following technical scheme: a kind of self-centering high-pressure on-off valve, including base, the upper slide connection of the base has inclined wedge block, the inclined wedge block is connected with cylinder along its sliding direction, the upper slide connection of the inclined wedge block has fixed seat, the upper of the fixed seat is equipped with the air guide rod of up and down setting, the first air guide hole of up and down through-penetration is equipped on the air guide rod, the air inlet hole of being communicated with first air guide hole is equipped on the fixed seat, the outer side of the air guide rod is slidably connected with guide rod sleeve, the outer side of the guide rod sleeve is equipped with upper cover, the passage for the installation of guide rod sleeve is equipped in the upper cover, the upper of the passage is connected with outlet hole, the diameter of the passage is greater than the diameter of outlet hole, the floating head is equipped in the passage, the floating head is located in the upper end of air guide rod and guide rod sleeve, the second air guide hole is equipped on the floating head, the passage below the floating head is communicated with outlet hole by the second air guide hole, the middle below the floating head is equipped with plugging head.

[0005] Further preferably, the floating head is a cylindrical structure, and the second air guide holes are evenly distributed along the circumferential direction of the floating head, which can ensure effective and uniform gas delivery. The lower side of the floating head is provided with a mounting groove of a stepped circular recess structure for accommodating the plugging head. The second air guide holes are arranged on one step in the mounting groove, and the plugging head is easily installed through the mounting groove.

[0006] Further preferably, the bottom of the mounting groove is provided with a first sealing groove along its circumferential direction, and a first sealing ring is embedded in the first sealing groove to seal between the blocking head and the floating head; the first sealing ring is above the blocking head, and the floating head is provided with a second sealing groove along its circumferential direction, and a second sealing ring is embedded in the second sealing groove to seal between the floating head and the upper cover.

[0007] Further preferably, the air inlet hole is horizontally arranged and connected with an air inlet connector for external connection of an air source; a sixth sealing ring is arranged between the air inlet connector and the fixed seat to ensure the sealing performance between the air inlet connector and the fixed seat.

[0008] Further preferably, the base is provided with a guide frame for guiding the wedge block, the guide frame is provided with a first guide hole penetrating up and down for guiding the fixed seat, the side edge of the guide frame is provided with a second guide hole penetrating along the sliding direction of the wedge block, and the guide frame is provided with a via hole for mounting the air inlet connector, so as to limit and guide the fixed seat and the wedge block through the guide frame.

[0009] Further preferably, the height of the wedge block close to the cylinder end is higher than that away from the cylinder end, the wedge block close to the cylinder end is provided with a connecting groove, and a push rod is connected with the connecting groove; the push rod is connected with the cylinder to realize the connection between the cylinder and the wedge block through the push rod.

[0010] Further preferably, the two opposite side edges of the base are each provided with a fixed block, and the upper part of the two fixed blocks is connected with a support flange; the support flange is connected with the guide rod sleeve to stably support the guide rod sleeve.

[0011] Further preferably, the upper surface of the fixed seat is provided with a plurality of vertically arranged mounting holes, each of which is provided with an elastic member, and the upper end of the elastic member abuts against the lower surface of the support flange. The elastic member can exert a downward force on the fixed seat, when the wedge block moves to the right, the lower end of the wedge block moves below the fixed seat, and the elastic member can drive the fixed seat and the air guide rod to move downward, so that the air guide rod is separated from the blocking head to realize the opening of the valve.

[0012] Further preferably, a plurality of third sealing rings are arranged between the outer side wall of the air guide rod and the inner wall of the guide rod sleeve, a plurality of fourth sealing rings are arranged between the outer side wall of the guide rod sleeve and the inner wall of the upper cover, and a plurality of fifth sealing rings are arranged between the lower end of the upper cover and the support flange to ensure the sealing effect between the air guide rod, the guide rod sleeve, the upper cover and the support flange.

[0013] Beneficial effects: the self-centering high-pressure on-off valve of the utility model, through the cylinder, the inclined wedge block, the fixed seat, the gas guide rod, the plugging head and the floating head form the floating, the centering structure, through the reciprocating motion of the cylinder can realize the on and off control of the high-pressure on-off valve, can ensure the sealing performance of the valve, guarantee the detection precision of the helium detection equipment applied by it;Specifically, the inclined wedge block is moved to the lower side of the fixed seat by the cylinder, the fixed seat and the gas guide rod are moved upward, the upper end of the gas guide rod is abutted with the plugging head, the plugging of the first gas guide hole is realized, the airflow cutting ability of the high-pressure on-off valve is realized;At the same time, when the plugging head is pressed on the gas guide rod, the self-centering effect of the floating head is realized through the cooperation of the gas guide rod and the plugging head, the sealing performance between the plugging head and the gas guide rod, the floating head and the upper cover is ensured, the sealing effect of the high-pressure on-off valve is strengthened, and internal leakage does not occur;When the low end of the inclined wedge block moves to the lower side of the fixed seat, under the action of the reaction of high-pressure gas and the elastic performance of the elastic member, the upper end of the gas guide rod is separated from the plugging head, at this time, the high-pressure gas in the first gas guide hole can enter the installation groove at the lower end of the channel and the floating head, enter the gas outlet hole through the second gas guide hole, and finally flow out, realizing the airflow conduction ability of the high-pressure on-off valve;

[0014] The high-pressure on-off valve realizes the up-down movement of the gas guide rod through the cylinder, the inclined wedge block and the fixed seat, thereby realizing the on and off control of the valve, is not affected by the action of high-pressure gas, can quickly and conveniently realize the on and off of the conveying gas, and is easy to control. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The utility model discloses a high-pressure on-off valve's axial measurement structure schematic diagram disclosed by the embodiment of the utility model;

[0016] Figure 2 The utility model discloses a high-pressure on-off valve's main view structure schematic diagram disclosed by the embodiment of the utility model;

[0017] Figure 3 The utility model discloses a high-pressure on-off valve's one sectional view structure schematic diagram disclosed by the embodiment of the utility model;

[0018] Figure 4 The utility model discloses a high-pressure on-off valve's another sectional view structure schematic diagram disclosed by the embodiment of the utility model;

[0019] Figure 5 The utility model discloses a floating head's structure schematic diagram disclosed by the embodiment of the utility model;

[0020] Figure 6 The utility model discloses a guide frame's structure schematic diagram disclosed by the embodiment of the utility model.

[0021] Reference numerals: 1-Base, 2-Fixing block, 3-Support flange, 4-Fixing seat, 41-Air inlet, 42-Mounting hole, 5-Air inlet connector, 6-Guide rod, 61-First air guide hole, 7-Guide rod sleeve, 8-Upper cover, 81-Channel, 82-Air outlet, 9-Floating head, 91-Second air guide hole, 92-Mounting groove, 93-First sealing groove, 94-Second sealing groove, 10-Sealing head, 11-Wedge block, 111-Connecting groove, 12-Cylinder, 13-Push rod, 14-Guide frame, 141-First guide hole, 142-Second guide hole, 143-Through hole, 15-Elastic element, 16-First sealing ring, 17-Second sealing ring, 18-Third sealing ring, 19-Fourth sealing ring, 20-Fifth sealing ring, 21-Sixth sealing ring. Detailed Implementation

[0022] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0023] like Figures 1-5 As shown, a self-aligning high-pressure on / off valve is used to control the on / off of gas. The high-pressure on / off valve includes a base 1, a wedge block 11 slidably connected above the base 1, a cylinder 12 connected to the wedge block 11 along its sliding direction, a fixed seat 4 slidably connected above the wedge block 11, a vertically arranged air guide rod 6 above the fixed seat 4, a first air guide hole 61 penetrating vertically on the air guide rod 6, an air inlet 41 communicating with the first air guide hole 61 on the fixed seat 4, and a guide rod sleeve 7 slidably connected to the outer side of the air guide rod 6. A cylinder 12 is sleeved on the outer side of the guide rod sleeve 7. The upper cover 8 has a channel 81 inside for installing the guide rod sleeve 7. An air outlet 82 is connected above the channel 81. The diameter of the channel 81 is larger than the diameter of the air outlet 82. A floating head 9 is provided inside the channel 81. The floating head 9 is located at the upper end of the air guide rod 6 and the guide rod sleeve 7. The floating head 9 has several second air guide holes 91. The channel 81 located below the floating head 9 is connected to the air outlet 82 through the second air guide holes 91. A sealing head 10 is provided in the middle below the floating head 9.

[0024] In the embodiment, the piston rod of the cylinder 12 can drive the wedge block 11 to move left and right, the wedge block 11 can drive the fixed seat 4 to move up and down, and the fixed seat 4 can drive the guide rod 6 to move up and down relative to the guide rod sleeve 7. When the guide rod 6 is in the low position, the high-pressure gas flowing into the guide rod 6 can blow upward, and the high-pressure gas in the guide rod 6 can enter the passage 81 below the floating head 9, then enter the gas outlet hole 82 through the second gas guide hole 91 on the floating head 9, and flow out through the gas outlet hole 82, so as to realize the gas conduction. When the guide rod 6 is in the high position, the floating head 9 can be pressed upward against the upper end surface of the passage 81, and the first gas guide hole 61 on the guide rod 6 can prevent the high-pressure gas from flowing upward, so as to realize the gas cut-off.

[0025] In the embodiment, the lower end of the sealing head 10 is in a semicircular arc shape, and the gas hole of the upper end of the guide rod 6 is in a horn shape. The lower end of the sealing head 10 can block the horn mouth of the first gas guide hole 61, so as to realize the sealing of the first gas guide hole 61. At the same time, the horn mouth is matched with the semicircular arc, so as to realize the position correction and centering of the sealing head 10, and then realize the position correction and centering of the floating head 9 with the floating amount, that is, realize the centering effect of the floating head 9 when the guide rod 6 is lifted and presses the sealing head 10, so as to ensure the sealing performance between the floating head 9 and the upper cover 8, and prevent the internal leakage of the high-pressure on-off valve.

[0026] In the embodiment, the guide rod sleeve 7 is used for guiding the guide rod 6, the upper cover 8 is used for presenting the passage 81 and the gas outlet hole 82, the passage 81 is used for installing the floating head 9, and the gas outlet hole 82 is used for guiding the gas out. The high-pressure on-off valve can be used on the helium detection equipment, so as to ensure the sealing performance of the valve body and the detection performance of the helium detection equipment.

[0027] As shown in Figure 5 , in one scheme of the application, the floating head 9 is in a cylindrical structure, has a floating amount, and can float in the passage 81. The plurality of second gas guide holes 91 are uniformly distributed along the circumferential direction of the floating head 9, the lower portion of the floating head 9 is provided with a mounting groove 92 in a stepped circular recess structure, and the second gas guide hole 91 is arranged on one step in the mounting groove 92.

[0028] Preferably, there are four second air guide holes 91, arranged in a cross structure at the front, rear, left, and right positions of the floating head 9. The four second air guide holes 91 can ensure the flow of gas. When high-pressure gas enters the channel 81 through the first air guide hole 61, the high-pressure gas will diffuse to all parts of the channel 81, and the four second air guide holes 91 can ensure the effective outflow of gas in the channel 81. The mounting groove 92 below the floating head 9 has a concave circular stepped groove structure, which facilitates the installation of the sealing head 10 and forms a high-pressure gas receiving cavity. Together with the sealing head 10, it forms an annular gas channel, which gathers the gas flowing into the channel 81 and facilitates its outflow through the second air guide holes 91 in the mounting groove 92.

[0029] Based on the above scheme, a first sealing groove 93 is provided at the bottom of the mounting groove 92 along its circumferential direction, and a first sealing ring 16 is embedded in the first sealing groove 93. The first sealing ring 16 is located above the sealing head 10. A second sealing groove 94 is provided above the floating head 9 along its circumferential direction, and a second sealing ring 17 is embedded in the second sealing groove 94.

[0030] The first sealing groove 93 is used for the installation of the first sealing ring 16, which seals the space between the plugging head 10 and the floating head 9, preventing gas from flowing through the gap between the plugging head 10 and the floating head 9, and then into the channel 81 and out through the second air guide hole 91, thus preventing leakage within the valve body. The second sealing groove 94 is used for the installation of the second sealing ring 17, which seals the space between the floating head 9 and the upper surface of the channel 81, preventing gas from flowing out through the gap between the floating head 9 and the inner wall of the channel 81. Simultaneously, placing the second sealing ring 17 above the floating head 9 prevents it from affecting the floating of the floating head 9.

[0031] In the scheme of this application, the air inlet 41 is horizontally arranged and connected to the air inlet connector 5. A sixth sealing ring 21 is provided between the air inlet connector 5 and the fixed base 4.

[0032] The air inlet 41 is located in front of the fixed base 4, perpendicular to the sliding direction of the wedge block 11. The air inlet 41 is connected to an air inlet connector 5, which facilitates connection to a gas source pipe for high-pressure gas transmission. A sixth sealing ring 21 seals the connection between the air inlet connector 5 and the fixed base 4, ensuring a tight seal between them.

[0033] like Figure 6 As shown, based on the above scheme, the base 1 is provided with a guide frame 14 for guiding the wedge block 11. The guide frame 14 is provided with a first guide hole 141 that passes through vertically for guiding the fixed seat 4. The side of the guide frame 14 is provided with a second guide hole 142 that passes through along the sliding direction of the wedge block 11. The guide frame 14 is provided with a through hole 143 for installing the air intake connector 5.

[0034] The guide frame 14 is used for limiting and guiding the fixed seat 4 and the wedge block 11. The first guide hole 141 is used for limiting the horizontal position of the fixed seat 4, and the fixed seat 4 can move up and down, and the moving direction is accurate. The second guide hole 142 is used for guiding the left and right movement of the wedge block 11, and the front and back positions are not offset. The left and right movement of the wedge block 11 moves the position of the inclined surface relative to the fixed seat 4 which is not moved horizontally. When the high end of the inclined surface moves towards the lower part of the fixed seat 4, the fixed seat 4 is lifted, and the air guide rod 6 above the fixed seat 4 is lifted to push against the plugging head 10, and the floating head 9 is tightly contacted with the upper end surface of the channel 81. At this time, the air guide rod 6 is in a sealed state, and the effect of cutting off the gas is realized. When the high end of the inclined surface of the wedge block 11 is away from the fixed seat 4, the fixed seat 4 and the air guide rod 6 move downward under the action of gas pressure, gravity or other forces (such as elastic force of the elastic member), and there is a gap between the upper end of the air guide rod 6 and the plugging head 10. High-pressure gas can enter the channel 81 and the mounting groove 92 through the gap, and flow out through the second air guide hole 91 and the air outlet hole 82, realizing the conduction of the gas. The hole 143 is convenient for the installation of the air inlet connector 5.

[0035] Preferably, the height of the end of the wedge block 11 close to the cylinder 12 is higher than the end away from the cylinder 12. When the piston rod of the cylinder 12 is extended, the wedge block 11 pushes the fixed seat 4 to rise, the air guide rod 6 rises, the plugging head 10 blocks the first air guide hole 61, the floating head 9 is centered and sealed with the channel 81, and at this time the high-pressure on-off valve is closed. When the piston rod of the cylinder 12 is retracted, the low end of the wedge block 11 is out of contact with the fixed seat 4, and at this time there is a gap between the upper end of the air guide rod 6 and the plugging head 10. The gas flows, that is, the high-pressure on-off valve is in an open state. The end of the wedge block 11 close to the cylinder 12 is provided with a connecting groove 111, the connecting groove 111 is connected with a push rod 13, the push rod 13 is connected with the cylinder 12, the connecting groove 111 is convenient for the plug-in connection of the push rod 13, the connection is convenient, and the left end of the push rod 13 is in T shape, which can be directly inserted into the connecting groove 111 to realize the quick connection of the connecting rod 13 and the wedge block 11. The push rod 13 is convenient for being connected with the cylinder 12.

[0036] In one scheme of the present application, the two opposite sides of the base 1 are each provided with a fixed block 2, the upper parts of the two fixed blocks 2 are connected with a support flange 3, and the support flange 3 is connected with the guide rod sleeve 7. The fixed block 2 is convenient for the installation of the support flange 3, and the support flange 3 is used for the installation and fixation of the guide rod sleeve 7. The fixed block 2 and the support flange 3 are used for the stable fixation of the guide rod sleeve 7, thereby ensuring the stable performance of the high-pressure on-off valve.

[0037] Based on the above scheme, the upper surface of the fixed seat 4 is provided with a plurality of vertically arranged mounting holes 42, and an elastic element 15 is arranged in each mounting hole 42. The upper end of the elastic element 15 abuts against the lower surface of the support flange 3. Through the arrangement of the elastic element 15, when the piston rod of the air cylinder 12 is retracted, the elastic element 15 can push the fixed seat 4 to move downward as the lower end of the wedge block 11 moves below the fixed seat 4, and pull the air guide rod 6 to move downward synchronously, so that the upper end of the air guide rod 6 is separated from the blocking head 10, and the airflow is communicated, that is, the elastic element 15 can assist the opening of the high-pressure on-off valve. In the present scheme, it is preferred that a limiting hole corresponding to the upper end of the elastic element 15 is arranged below the support flange 3 to ensure the stable installation of the elastic element 15 and the accurate release direction of the force. At the same time, the elastic element 15 is preferably a spring.

[0038] Based on the above scheme, a plurality of third sealing rings 18 are arranged between the outer side wall of the air guide rod 6 and the inner wall of the guide rod sleeve 7 to ensure the sealing effect between the air guide rod 6 and the guide rod sleeve 7; a plurality of fourth sealing rings 19 are arranged between the outer side wall of the guide rod sleeve 7 and the inner wall of the upper cover 8 to ensure the sealing effect between the guide rod sleeve 7 and the upper cover 8; and a plurality of fifth sealing rings 20 are arranged between the lower end of the upper cover 8 and the support flange 3 to ensure the sealing effect between the upper cover 8 and the support flange 3; that is, the third sealing ring 18, the fourth sealing ring 19 and the fifth sealing ring 20 can ensure the sealing effect of the channel 81 of the upper cover 8, thereby ensuring the sealing effect of the high-pressure on-off valve and further preventing internal leakage to ensure the detection performance of the helium detection equipment.

[0039] Finally, it should be noted that: the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A self-aligning high pressure on-off valve comprising a base (1), characterized in that: The upper side of the base (1) is slidably connected with a wedge block (11), the wedge block (11) is connected with a cylinder (12) along the sliding direction, the upper side of the wedge block (11) is slidably connected with a fixed seat (4), the upper side of the fixed seat (4) is provided with an air guide rod (6) arranged in an up-down mode, the air guide rod (6) is provided with a first air guide hole (61) penetrating in an up-down mode, the fixed seat (4) is provided with an air inlet hole (41) in communication with the first air guide hole (61), the outer side of the air guide rod (6) is slidably connected with a guide rod sleeve (7), the outer side of the guide rod sleeve (7) is sleeved with an upper cover (8), the upper cover (8) is internally provided with a channel (81) for mounting the guide rod sleeve (7), the upper side of the channel (81) is connected with an air outlet hole (82), the diameter of the channel (81) is greater than that of the air outlet hole (82), the channel (81) is internally provided with a floating head (9), the floating head (9) is located at the upper end of the air guide rod (6) and the guide rod sleeve (7), the floating head (9) is provided with a plurality of second air guide holes (91), the channel (81) below the floating head (9) is in communication with the air outlet hole (82) through the second air guide holes (91), the lower side of the floating head (9) is provided with a plugging head (10).

2. A self-aligning high pressure on-off valve according to claim 1, characterized in that: The floating head (9) is in a cylindrical structure, the plurality of second air guide holes (91) are uniformly arranged along the circumferential direction of the floating head (9), the lower side of the floating head (9) is provided with a mounting groove (92) in a stepped circular groove structure for accommodating the plugging head (10), and the second air guide holes (91) are arranged on one step in the mounting groove (92).

3. A self-aligning high pressure on-off valve according to claim 2, characterized in that: The bottom of the mounting groove (92) is provided with a first sealing groove (93) along the circumferential direction, the first sealing groove (93) is embedded with a first sealing ring (16), and the first sealing ring (16) is located above the plugging head (10); the upper side of the floating head (9) is provided with a second sealing groove (94) along the circumferential direction, and the second sealing groove (94) is embedded with a second sealing ring (17).

4. A self-aligning high pressure on-off valve as claimed in claim 1, wherein: The air inlet hole (41) is horizontally arranged and is connected with an air inlet connector (5), and the air inlet connector (5) and the fixed seat (4) are provided with a sixth sealing ring (21).

5. A self-aligning high pressure on-off valve according to claim 4, characterized in that: The base (1) is provided with a guide frame (14) for guiding the wedge block (11), the guide frame (14) is provided with a first guide hole (141) penetrating in an up-down mode for guiding the fixed seat (4), the side edge of the guide frame (14) is provided with a second guide hole (142) penetrating along the sliding direction of the wedge block (11), and the guide frame (14) is provided with a via hole (143) for mounting the air inlet connector (5).

6. A self-aligning high pressure on-off valve as claimed in claim 1, wherein: The height of the end of the wedge block (11) close to the cylinder (12) is higher than that of the end away from the cylinder (12), the end of the wedge block (11) close to the cylinder (12) is provided with a connecting groove (111), the connecting groove (111) is connected with a push rod (13), and the push rod (13) is connected with the cylinder (12).

7. A self-aligning high pressure on-off valve as claimed in claim 1, wherein: Two opposite sides of the base (1) are provided with a fixed block (2), and the upper portions of the two fixed blocks (2) are connected with a supporting flange (3), and the supporting flange (3) is connected with a guide rod sleeve (7).

8. A self-aligning high pressure on-off valve according to claim 7, characterized in that: The upper surface of the fixed seat (4) is provided with a plurality of vertically arranged mounting holes (42), and each mounting hole (42) is provided with an elastic member (15), and the upper end of the elastic member (15) abuts against the lower surface of the supporting flange (3).

9. A self-aligning high pressure on-off valve as claimed in claim 7, wherein: The outer side wall of the air guide rod (6) and the inner wall of the guide rod sleeve (7) are provided with a plurality of third sealing rings (18), the outer side wall of the guide rod sleeve (7) and the inner wall of the upper cover (8) are provided with a plurality of fourth sealing rings (19), and the lower end of the upper cover (8) and the supporting flange (3) are provided with a plurality of fifth sealing rings (20).

Images