Double-valve-plate and negative-pressure sealed fluid medium control valve and sealing method

Abstract

The invention discloses a fluid medium control valve with double valve plates and negative pressure sealing and a sealing method. The fluid medium control valve comprises a valve body, a valve rod, the valve plates, an actuator and a valve seat. The valve plate comprises a front valve plate and a rear valve plate which are sequentially arranged in the fluid medium conveying direction, the valve seat comprises a front valve seat corresponding to the front valve plate and a rear valve seat corresponding to the rear valve plate, and a double-valve-plate sealing structure is formed in the state that the front valve plate abuts against the front valve seat in a sealed mode and the rear valve plate abuts against the rear valve seat in a sealed mode. A sealing cavity is formed between the front valve plate and the rear valve plate in the valve body; under the pressure difference state that the internal pressure intensity of the sealing cavity is smaller than the external pressure intensity through air exhaust of the sealing cavity, the front valve plate and the rear valve plate located at the two ends of the sealing cavity tightly abut against the corresponding front valve seat and the corresponding rear valve seat through the negative pressure effect. Double-valve-plate sealing and negative-pressure sealing are carried out on the control valve, and the sealing performance of the control valve can be greatly improved when the control valve is closed.

Description

Technical Field

[0001] The present invention belongs to the technical field of butterfly valves, and in particular relates to a fluid medium control valve with double valve plates and negative pressure sealing and a sealing method. Background Art

[0002] Butterfly valves play a vital role in the field of semiconductor production. They are mainly used to accurately control the flow of fluid media including various chemical gases, liquids and steam to ensure metering and transportation in the semiconductor manufacturing process. Since the existing butterfly valves adopt a single valve plate structure, and the valve plate adopts a metal valve plate based on service life and structural strength, there will be a small amount of fluid leakage in the closed valve sealing state, and the sealing performance needs to be improved. Summary of the invention

[0003] Purpose of the invention: In order to overcome the shortcomings of the prior art, the present invention provides a fluid medium control valve and sealing method with double valve plates and negative pressure seals. By performing double valve plate sealing and negative pressure sealing on the control valve, the sealing performance of the control valve when closing the valve can be greatly improved, solving the problem of small leakage of the fluid medium.

[0004] Technical solution: To achieve the above purpose, a fluid medium control valve with double valve plates and negative pressure seal of the present invention comprises a valve body, a valve stem, a valve plate and an actuator. The valve plate is arranged in the valve body through the rotational cooperation of the valve stem, so that the valve plate cooperates with the valve seat in the valve body, and the actuator drives the valve stem to drive the valve plate to rotate;

[0005] The valve plate comprises a front valve plate and a rear valve plate arranged in sequence along the fluid medium conveying direction, the valve seat comprises a front valve seat arranged corresponding to the front valve plate and a rear valve seat arranged corresponding to the rear valve plate, the front valve plate and the front valve seat are sealed against each other and the rear valve plate and the rear valve seat are sealed against each other, forming a double valve plate sealing structure;

[0006] A sealed cavity is formed between the front valve plate and the rear valve plate in the valve body, and the sealed cavity has an air port located on the valve body. The sealed cavity is evacuated or inflated through the air port to change the pressure inside the sealed cavity. When the sealed cavity is evacuated to create a pressure difference that makes the internal pressure of the sealed cavity less than the external pressure, the front valve plate and the rear valve plate located at both ends of the sealed cavity are tightly pressed against the corresponding front valve seat and rear valve seat through the negative pressure effect.

[0007] Furthermore, when the valve plate and the valve seat are in a sealed cooperation state, the pressure inside the sealing cavity is P1, the pressure on the front valve plate side outside the sealing cavity is P2, and the pressure on the rear valve plate side outside the sealing cavity is P3, satisfying the relationship: P1﹤P3﹤P2.

[0008] Furthermore, the inner ring of the front valve seat has a gradually shrinking structure in the direction of fluid medium conveying, and the front valve plate is sealed against the inner ring inclined surface of the front valve seat; the inner ring of the rear valve seat has a gradually expanding structure in the direction of fluid medium conveying, and the rear valve plate is sealed against the inner ring inclined surface of the rear valve seat.

[0009] Furthermore, the outer edge of the valve plate has a flexible sealing edge, and when the valve plate is in a sealed state against the valve seat, the flexible sealing edge fits the valve seat.

[0010] Furthermore, a radial dimension of the front valve plate is greater than a radial dimension of the rear valve plate.

[0011] Furthermore, the valve stem includes a front valve stem correspondingly connected to the front valve plate and a rear valve stem correspondingly connected to the rear valve plate; a gear set is provided corresponding to the double valve plate sealing structure to transmission connect the front valve stem and the rear valve stem, and the gear set drives a servo motor connected to the actuator so that the front valve plate and the rear valve plate maintain synchronous rotation to open and close the valve.

[0012] Furthermore, a pressure plate, a connecting seat and a limit plate are sequentially arranged between the valve body and the actuator from the upper guide; an upper valve stem packing is embedded in the connecting seat, a lower valve stem packing is embedded in the valve body, the valve stem passes through the upper valve stem packing and the lower valve stem packing in sequence, the power input end of the valve stem is connected to a gear set, the end of the valve stem extending into the valve body is connected to the valve plate, and a rotation stroke limiting structure is arranged between the valve stem and the limit plate.

[0013] Furthermore, the rotational stroke limiting structure includes a movable part located on the valve stem and a fixed part located on the inner hole wall of the limit plate, and the fixed part is located on the rotational path of the movable part; the valve stem drives the valve plate to rotate to the safe valve opening position and the fully valve closing position, and the stroke limit is achieved by the fixed part blocking the movable part.

[0014] Furthermore, the air port on the valve body is connected to an electric valve, and the electric valve is connected to an air extraction device through a pipeline.

[0015] A sealing method for a fluid medium control valve with double valve plates and negative pressure sealing, comprising a double valve plate sealing stage and a negative pressure sealing stage performed sequentially, specifically as follows:

[0016] Double valve plate sealing stage: The actuator drives the front valve stem and the rear valve stem to rotate through the gear set, and then synchronously drives the connected front valve plate and the rear valve plate to rotate. The front valve plate rotates to abut against the front valve seat, and the rear valve plate rotates to abut against the rear valve seat, thereby forming a double valve plate sealing structure. The double valve plate sealing of the control valve is achieved through the double valve plate sealing structure;

[0017] Negative pressure sealing stage: Based on the double valve plate sealing, the front valve plate and the rear valve plate form a sealing cavity in the valve body; at this time, due to the accumulation of fluid medium, the pressure P2 on the front valve plate side is positive pressure; due to the exhaust of fluid medium, the pressure P3 on the rear valve plate side is the same as the external pressure, which is normal pressure; open the electric valve, start the vacuum equipment to evacuate the sealing cavity, so that the pressure P1 inside the sealing cavity is negative pressure; thus satisfying the relationship: P1﹤P3﹤P2, and based on the relationship of P1﹤P3﹤P2, under the action of the negative pressure effect, the flexible sealing edge on the front valve plate is tightly fitted to the front valve seat, and the flexible sealing edge on the rear valve plate is tightly fitted to the rear valve seat, thereby realizing the negative pressure sealing of the control valve;

[0018] The double valve plate sealing stage is executed first, and the negative pressure sealing stage is executed based on the double valve plate sealing stage. In the negative pressure sealing stage, the double valve plate sealing and the negative pressure sealing coexist, thereby realizing the double valve plate sealing and negative pressure sealing of the control valve.

[0019] Beneficial effect: The present invention can greatly improve the sealing performance of the control valve when closing the valve and solve the problem of small leakage of fluid medium by performing double valve plate sealing and negative pressure sealing on the control valve. The double valve plate seal is different from the single valve plate seal of the existing butterfly valve. It provides two sealing barriers for the valve, which plays a more reliable and stable sealing role. The negative pressure seal is achieved on the basis of the double valve plate seal. Under the action of the negative pressure effect, the flexible sealing edge can fit tightly against the valve seat, further improving the sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the fluid medium control valve with double valve negative pressure seal of the present invention;

[0021] Figure 2 It is a schematic diagram of a half-section structure of a fluid medium control valve with double valve negative pressure seal of the present invention;

[0022] Figure 3 It is a schematic diagram of the half-section structure of the valve body;

[0023] Figure 4 It is a structural schematic diagram of the valve stem and valve plate. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] like Figure 1 , Figure 2 as well as Figure 3As shown, a fluid medium control valve with double valve plates and negative pressure sealing includes a valve body 1, a valve stem 2, a valve plate 3 and an actuator 4. The valve plate 3 is arranged in the valve body 1 through the rotation of the valve stem 2, so that the valve plate 3 cooperates with the valve seat 5 in the valve body 1, and the actuator 4 drives the valve stem 2 to drive the valve plate 3 to rotate; the valve plate 3 includes a front valve plate 31 and a rear valve plate 32 arranged in sequence along the fluid medium conveying direction, the valve seat 5 includes a front valve seat 51 arranged corresponding to the front valve plate 31 and a rear valve seat 52 arranged corresponding to the rear valve plate 32, the front valve plate 31 is sealed against the front valve seat 51 and the rear valve plate 3 2 and the rear valve seat 52 are in a sealed state, forming a double valve plate sealing structure; a sealed cavity 10 is formed between the front valve plate 31 and the rear valve plate 32 in the valve body 1, and the sealed cavity 10 has an air port 11 located on the valve body 1, and the sealed cavity 10 is evacuated or inflated through the air port 11 to change the pressure inside the sealed cavity 10; when the sealed cavity 10 is evacuated so that the internal pressure of the sealed cavity 10 is less than the external pressure, the front valve plate 31 and the rear valve plate 32 at both ends of the sealed cavity 10 are tightly against the corresponding front valve seat 51 and the rear valve seat 52 through the negative pressure effect. Figure 4 As shown, the outer edge of the valve plate 3 has a flexible sealing edge 30, and when the valve plate 3 is in a sealed state against the valve seat 5, the flexible sealing edge 30 fits the valve seat 5. The present invention can greatly improve the sealing performance of the control valve when the valve is closed by performing double valve plate sealing and negative pressure sealing on the control valve, and solve the problem of a small amount of leakage of the fluid medium. The double valve plate sealing is different from the single valve plate sealing of the existing butterfly valve, and it provides two sealing barriers for the valve, which plays a more reliable and stable sealing role. The negative pressure sealing is realized on the basis of the double valve plate sealing. Under the action of the negative pressure effect, the flexible sealing edge 30 can be closely fitted to the valve seat 5, further improving the sealing performance.

[0026] like Figure 3 As shown, when the valve plate 3 and the valve seat 5 are in a sealed cooperation state, the pressure inside the sealed cavity 10 is P1, the pressure on the side of the front valve plate 31 outside the sealed cavity 10 is P2, and the pressure on the side of the rear valve plate 32 outside the sealed cavity 10 is P3. Due to the accumulation of fluid medium, the pressure P2 on the side of the front valve plate 31 is positive pressure, and due to the exhaustion of fluid medium, the pressure P3 on the side of the rear valve plate 32 is the same as the external pressure, which is normal pressure. The pressure P1 inside the sealed cavity 10 is negative pressure due to the suction effect. Therefore, the relationship is satisfied: P1﹤P3﹤P2, thereby having the conditions for generating a negative pressure effect.

[0027] It is worth noting that in order to improve the stability of the valve plate 3 and the valve seat 5 when they are sealed together and to avoid the plate coming off and affecting the sealing or causing sealing failure, in the present invention, the inner ring of the front valve seat 51 is in a gradually shrinking structure in the direction of fluid medium conveying, and the front valve plate 31 is against the inner ring inclined surface of the front valve seat 51 to achieve sealing; the inner ring of the rear valve seat 52 is in a gradually expanding structure in the direction of fluid medium conveying, and the rear valve plate 32 is against the inner ring inclined surface of the rear valve seat 52 to achieve sealing.

[0028] More specifically, based on the flow direction of the fluid medium from the position of the front valve plate 31 to the position of the rear valve plate 32, in order to maintain the fullness of the pipeline after the fluid medium is released through the control valve and avoid partial emptiness in the pipeline, the radial dimension of the front valve plate 31 is greater than the radial dimension of the rear valve plate 32.

[0029] like Figure 2 , Figure 3 and Figure 4 As shown, the valve stem 2 includes a front valve stem 21 correspondingly connected to the front valve plate 31 and a rear valve stem 22 correspondingly connected to the rear valve plate 32; a gear set 6 is provided corresponding to the double valve plate sealing structure to drive and connect the front valve stem 21 and the rear valve stem 22, and the gear set 6 drives the servo motor 21 connected to the actuator 4, so that the front valve plate 31 and the rear valve plate 32 maintain synchronous rotation to open and close the valve. The gear set 6 uses three gears, the middle one is a driving gear connected to the servo motor 21, and the two sides are driven gears respectively connected to the front valve stem 21 and the rear valve stem 22, and the output shaft of the servo motor 21 is connected to the gear shaft of the driving gear through a coupling.

[0030] like Figure 3 As shown, a pressure plate 7, a connecting seat 8 and a limit plate 9 are sequentially arranged between the valve body 1 and the actuator 4 from the upper guide; an upper valve stem packing 15 is embedded in the connecting seat 8, and a lower valve stem packing 16 is embedded in the valve body 1. The valve stem 2 passes through the upper valve stem packing 15 and the lower valve stem packing 16 in sequence. The power input end of the valve stem 2 is connected to the gear set 6, and the end of the valve stem 2 extending into the valve body 1 is connected to the valve plate 3, and a rotation stroke limit structure 17 is arranged between the valve stem 2 and the limit plate 9. More specifically, as Figure 4 As shown, the rotational stroke limiting structure 17 includes a movable portion 17a located on the valve stem 2 and a fixed portion 17b located on the wall of the inner hole 90 of the limiting plate 9, and the fixed portion 17b is located on the rotational activity path of the movable portion 17a; the valve stem 2 drives the valve plate 3 to rotate to the safe valve opening position and the fully valve closing position, and the stroke limiting is achieved by the fixed portion 17b blocking the movable portion 17a.

[0031] The gas port 11 on the valve body 1 is connected to an electric valve 18 , and the electric valve 18 is connected to an air extraction device 20 via a pipeline 19 .

[0032] A sealing method for a fluid medium control valve with double valve plates and negative pressure sealing, comprising a double valve plate sealing stage and a negative pressure sealing stage performed sequentially, specifically as follows:

[0033] Double valve plate sealing stage: the actuator 4 drives the front valve stem 21 and the rear valve stem 22 to rotate through the gear set 6, thereby synchronously driving the connected front valve plate 31 and the rear valve plate 32 to rotate, the front valve plate 31 rotates to abut against the front valve seat 51, and the rear valve plate 32 rotates to abut against the rear valve seat 52, thereby forming a double valve plate sealing structure, and the double valve plate sealing of the control valve is achieved through the double valve plate sealing structure;

[0034] Negative pressure sealing stage: Based on the double valve plate sealing, the front valve plate 31 and the rear valve plate 32 form a sealed cavity 10 in the valve body 1; at this time, due to the accumulation of fluid medium, the pressure P2 on one side of the front valve plate 31 is positive pressure; due to the exhaustion of fluid medium, the pressure P3 on one side of the rear valve plate 32 is the same as the external pressure, which is normal pressure; open the electric valve 18, start the vacuum device 20 to evacuate the sealed cavity 10, so that the pressure P1 inside the sealed cavity 10 is negative pressure; thereby satisfying the relationship: P1﹤P3﹤P2, and based on the relationship of P1﹤P3﹤P2, under the action of the negative pressure effect, the flexible sealing edge 30 on the front valve plate 31 is tightly fitted to the front valve seat 51, and the flexible sealing edge 30 on the rear valve plate 32 is tightly fitted to the rear valve seat 52, thereby realizing negative pressure sealing of the control valve;

[0035] The double valve plate sealing stage is executed first, and the negative pressure sealing stage is executed based on the double valve plate sealing stage. In the negative pressure sealing stage, the double valve plate sealing and the negative pressure sealing coexist, thereby realizing the double valve plate sealing and negative pressure sealing of the control valve.

[0036] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary personnel in this field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A fluid medium control valve with double valve plates and negative pressure sealing, comprising a valve body (1), a valve stem (2), a valve plate (3) and an actuator (4), wherein the valve plate (3) is arranged in the valve body (1) by rotating the valve stem (2), so that the valve plate (3) is matched with a valve seat (5) in the valve body (1), and the actuator (4) drives the valve stem (2) to drive the valve plate (3) to rotate; Features: The valve plate (3) comprises a front valve plate (31) and a rear valve plate (32) which are sequentially arranged along the direction of fluid medium conveyance, and the valve seat (5) comprises a front valve seat (51) which is arranged corresponding to the front valve plate (31) and a rear valve seat (52) which is arranged corresponding to the rear valve plate (32). The front valve plate (31) and the front valve seat (51) are sealed against each other, and the rear valve plate (32) and the rear valve seat (52) are sealed against each other, thereby forming a double valve plate sealing structure. A sealed cavity (10) is formed between the front valve plate (31) and the rear valve plate (32) in the valve body (1), and the sealed cavity (10) has an air port (11) located on the valve body (1). The sealed cavity (10) is evacuated or inflated through the air port (11), thereby changing the pressure inside the sealed cavity (10); when the sealed cavity (10) is evacuated so that the internal pressure of the sealed cavity (10) is less than the external pressure, the front valve plate (31) and the rear valve plate (32) located at the two ends of the sealed cavity (10) are tightly pressed against the corresponding front valve seat (51) and the rear valve seat (52) through the negative pressure effect.

2. A fluid medium control valve with double valve plates and negative pressure seal according to claim 1, characterized in that: When the valve plate (3) and the valve seat (5) are in a sealed fit, the pressure inside the sealed chamber (10) is P1, the pressure on the front valve plate (31) side outside the sealed chamber (10) is P2, and the pressure on the rear valve plate (32) side outside the sealed chamber (10) is P3, satisfying the relationship: P1﹤P3﹤P2.

3. A fluid medium control valve with double valve plates and negative pressure seal according to claim 2, characterized in that: The inner ring of the front valve seat (51) is in a gradually contracting structure in the direction of fluid medium conveying, and the front valve plate (31) abuts against the inner ring inclined surface of the front valve seat (51) to achieve sealing; the inner ring of the rear valve seat (52) is in a gradually expanding structure in the direction of fluid medium conveying, and the rear valve plate (32) abuts against the inner ring inclined surface of the rear valve seat (52) to achieve sealing.

4. A fluid medium control valve with double valve plates and negative pressure seal according to claim 3, characterized in that: The outer edge of the valve plate (3) has a flexible sealing edge (30), and when the valve plate (3) is in a sealed state against the valve seat (5), the flexible sealing edge (30) fits the valve seat (5).

5. A fluid medium control valve with double valve plates and negative pressure seal according to claim 3, characterized in that: The radial dimension of the front valve plate (31) is greater than the radial dimension of the rear valve plate (32).

6. A fluid medium control valve with double valve plates and negative pressure seal according to claim 5, characterized in that: The valve stem (2) comprises a front valve stem (21) correspondingly connected to the front valve plate (31) and a rear valve stem (22) correspondingly connected to the rear valve plate (32); a gear set (6) is provided corresponding to the double valve plate sealing structure for transmission connecting the front valve stem (21) and the rear valve stem (22); the gear set (6) drives a servo motor (21) connected to the actuator (4) so ​​that the front valve plate (31) and the rear valve plate (32) maintain synchronous rotation to open and close the valve.

7. A fluid medium control valve with double valve plates and negative pressure seal according to claim 6, characterized in that: A pressure plate (7), a connecting seat (8) and a limit plate (9) are arranged in sequence from the upper guide between the valve body (1) and the actuator (4); an upper valve stem packing (15) is embedded in the connecting seat (8), and a lower valve stem packing (16) is embedded in the valve body (1); the valve stem (2) passes through the upper valve stem packing (15) and the lower valve stem packing (16) in sequence; the power input end of the valve stem (2) is connected to the gear set (6), the end of the valve stem (2) extending into the valve body (1) is connected to the valve plate (3), and a rotation stroke limit structure (17) is arranged between the valve stem (2) and the limit plate (9).

8. A fluid medium control valve with double valve plates and negative pressure seal according to claim 7, characterized in that: The rotational stroke limiting structure (17) comprises a movable portion (17a) located on the valve stem (2) and a fixed portion (17b) located on the wall of the inner hole (90) of the limiting plate (9), wherein the fixed portion (17b) is located on the rotational movement path of the movable portion (17a); the valve stem (2) drives the valve plate (3) to rotate to a safe valve opening position and a fully valve closing position, and the stroke limiting is achieved by blocking the movable portion (17a) by the fixed portion (17b).

9. A fluid medium control valve with double valve plates and negative pressure seal according to claim 7, characterized in that: The gas port (11) on the valve body (1) is connected to an electric valve (18), and the electric valve (18) is connected to an air extraction device (20) via a pipeline (19).

10. The sealing method of a double valve plate and a negative pressure sealed fluid medium control valve according to claim 9, characterized in that: It includes a double valve plate sealing stage and a negative pressure sealing stage which are performed in sequence, as follows: Double valve plate sealing stage: the actuator (4) drives the front valve stem (21) and the rear valve stem (22) to rotate through the gear set (6), thereby synchronously driving the connected front valve plate (31) and the rear valve plate (32) to rotate, the front valve plate (31) rotates to abut against the front valve seat (51), and the rear valve plate (32) rotates to abut against the rear valve seat (52), thereby forming a double valve plate sealing structure, and realizing double valve plate sealing of the control valve through the double valve plate sealing structure; Negative pressure sealing stage: Based on the double valve plate sealing, the front valve plate (31) and the rear valve plate (32) form a sealed cavity (10) in the valve body (1); at this time, due to the accumulation of fluid medium, the pressure P2 on one side of the front valve plate (31) is positive pressure; due to the exhaustion of fluid medium, the pressure P3 on one side of the rear valve plate (32) is the same as the external pressure, that is, normal pressure; the electric valve (18) is opened, and the exhaust device (20) is started to exhaust air from the sealed cavity (10), so that the pressure P1 inside the sealed cavity (10) is negative pressure; thereby satisfying the relationship: P1﹤P3﹤P2, and based on the relationship of P1﹤P3﹤P2, under the action of the negative pressure effect, the flexible sealing edge (30) on the front valve plate (31) is tightly fitted to the front valve seat (51), and the flexible sealing edge (30) on the rear valve plate (32) is tightly fitted to the rear valve seat (52), thereby realizing negative pressure sealing of the control valve; The double valve plate sealing stage is executed first, and the negative pressure sealing stage is executed based on the double valve plate sealing stage. In the negative pressure sealing stage, the double valve plate sealing and the negative pressure sealing coexist, thereby realizing the double valve plate sealing and negative pressure sealing of the control valve.

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