Control method of charging gun

Abstract

The present invention discloses a control method for a charging gun, comprising: obtaining a charging pressure P1 of the charging gun before opening the charging gun; filling a first molecular quantity of gas n1 into a first pressure chamber in a pressure compensation chamber so that the pressure P2 in the first pressure chamber reaches 1 / 2 of the charging pressure P1, at which time the sealing tube is in a stretched state, and the volume corresponding to the first pressure chamber is V1; controlling the valve stem to move downward so that the valve port is opened and the opening is increased to a working state; opening the valve of the charging pipeline so that the second pressure chamber is connected to the charging pipeline, so that the material enters the second pressure chamber and is charged through the valve port. The control method for the charging gun provided by the present invention can reduce the pressure difference between the inside and outside of the sealing tube by supplementing the pressure of the pressure compensation chamber to reduce the pressure difference between the inside and outside of the sealing tube, thereby reducing the pressure on the sealing tube due to the operation of the filling gun and extending the service life of the sealing tube.

Description

Technical Field

[0001] The present invention relates to the field of filling equipment, in particular to a control method for a filling gun. Background Art

[0002] During the filling process, the filling equipment requires a filling gun to complete the final filling of the material. Since the filling gun needs to be opened and closed by a control valve, and the control valve adopts a long rod structure, the valve stem of the control valve adopts a sliding seal with the seal during the extension and retraction process, which not only has friction resistance, but also because there is a pressure difference between the pressure in the valve cavity and the external pressure during the control process of the control valve. This pressure difference makes the movement of the control valve stem difficult. Summary of the Invention

[0003] The technical problem to be solved by the embodiments of the present invention is to provide a control method for a filling gun to solve the problem that the movement of the valve stem causes the volume of the pressure compensation chamber to increase, resulting in a decrease in pressure, and further causes an increase in the pressure difference between the inside and outside of the sealing tube.

[0004] In order to solve the above technical problems, the present invention provides a control method for a charging gun, comprising:

[0005] Before opening the charging gun, obtain the charging pressure P1 of the charging gun;

[0006] The first pressure chamber in the pressure compensation chamber is filled with a first number of gas molecules n1, so that the pressure P2 in the first pressure chamber reaches 1 / 2 of the filling pressure P1. At this time, the sealing tube is in a stretched state, and the corresponding volume of the first pressure chamber is V1.

[0007] The control valve stem moves downward to open the valve port and increase the opening to the working state. This action compresses the sealing tube and increases the volume of the first pressure chamber to V2. At this time, the second number of gas molecules n2 is filled into the pressure compensation chamber, raising the pressure of the first pressure chamber to 1 / 2 of the filling pressure P1; V1:V2=n1:(n1+n2);

[0008] Open the valve of the charging pipeline to connect the second pressure chamber with the charging pipeline, so that the material enters the second pressure chamber and is charged through the valve port.

[0009] When filling is completed, close the valve of the filling pipeline;

[0010] Blow air into the charging pipeline to clear the residual material in the second pressure chamber;

[0011] The pressure in the first pressure chamber is controlled to decrease, and then the valve stem is controlled to move upward, so that the pressure in the first pressure chamber during the upward movement of the valve stem is lower than 1 / 2 of the charging pressure.

[0012] The sealing tube between the first pressure chamber and the second pressure chamber is preferably a bellows;

[0013] Optionally, when the sealing tube is a bellows, an inner steel ring is preferably provided in the inner corner of the convex large ring of the bellows, and an outer steel ring is provided in the outer corner of the concave small ring of the bellows.

[0014] The volume parameters V1 and V2 are calculated by modeling the working state of the filling gun.

[0015] The pressure P2 of the first pressure chamber is obtained through a pressure gauge provided on the pressure compensation port of the pressure compensation chamber.

[0016] The present invention provides a method for controlling a charging gun, comprising:

[0017] Control the valve stem to move downward, open the valve port and increase the opening of the valve port;

[0018] Open the valve of the charging pipeline to connect the second pressure chamber with the charging pipeline, so that the material enters the second pressure chamber and is charged through the valve port;

[0019] While opening the valve of the charging pipeline, the first pressure chamber in the pressure compensation chamber is pressurized to increase the pressure in the first pressure chamber, and the pressure difference between the first pressure chamber and the second pressure chamber is maintained within a preset range, for example, within ±0.1 MPa;

[0020] The pressure of the first pressure chamber and the pressure of the second pressure chamber are adjusted to a balanced state.

[0021] The charging gun includes:

[0022] Lower straight pipe with a filling port at the bottom;

[0023] A three-way cavity, the bottom of which is connected to the lower straight pipe and the side wall of which is connected to the filling pipe;

[0024] A pressure compensation chamber is connected to the three-way chamber;

[0025] The valve stem comprises a main stem and a connecting rod, wherein the connecting rod is connected to the lower end of the main stem, the main stem passes through the three-way cavity and the pressure compensation cavity, and the connecting rod is located in the lower straight tube;

[0026] The valve head is connected to the lower end of the connecting rod, and the valve head can be sealed and connected to the filling port of the lower straight pipe or opened;

[0027] In which, the main rod and the upper end of the pressure compensation chamber are slidingly and sealedly connected through a first guide washer; a retractable sealing tube is provided in the pressure compensation chamber, and the sealing tube is sleeved on the main rod, the top of the sealing tube is fixed and sealed to the outer wall of the main rod, and the bottom of the sealing tube is clamped and sealed by the pressure compensation chamber and the three-way chamber, so that the sealing tube divides the space in the pressure compensation chamber into two inner and outer chambers: a cylindrical second pressure chamber is formed by the main rod, the connecting rod, the lower straight tube and the sealing tube, the second pressure chamber serves as a working chamber, and a cylindrical first pressure chamber is formed by the inner wall of the pressure compensation chamber, the sealing tube, the main rod and the first guide washer, and the first pressure chamber is used to compensate for the pressure of the working chamber.

[0028] A pressure compensation port is provided on the pressure compensation cavity. When the volume of the first pressure chamber increases, pressure is charged into the first pressure chamber through the pressure compensation port to reduce the pressure difference between the first pressure chamber and the second pressure chamber.

[0029] The pressure compensation port is provided with a pressure valve. When the main rod moves downward, pressure is charged into the pressure compensation cavity through the pressure valve.

[0030] A second guide washer is further provided on the top of the three-way cavity. The second guide washer is provided with a hole communicating with each other up and down to connect the sealing tube and the three-way cavity.

[0031] The sealing tube is a bellows structure and is made of elastic rubber material.

[0032] The main rod is provided with a necking structure, namely a first section with a larger diameter and a second section with a smaller diameter, wherein the first section is slidingly connected to the first guide washer and the second section is slidingly connected to the second guide washer; the upper end of the sealing tube is connected to the first section, and the second section is located inside the sealing tube.

[0033] A locking ring is provided at the upper end of the sealing tube to lock and fix the sealing tube and the main rod; optionally, a ring-cut locking groove is provided on the main rod to enable the locking ring to press the sealing tube into the locking groove.

[0034] The lower end of the sealing tube is clamped and fixed by the pressure compensation cavity and the three-way cavity.

[0035] The top of the pressure compensation chamber is provided with a first top plate, the bottom is provided with a first bottom plate, and the center hole of the first top plate is provided with an annular step surface for accommodating a first guide washer.

[0036] The top of the three-way cavity is provided with a second top plate, the bottom is provided with a second bottom plate, and the second top plate is provided with a through hole for accommodating the second guide washer; wherein the first bottom plate and the second top plate are butted together and clamp and seal the bottom of the sealing tube.

[0037] The control method of the charging gun provided by the present invention can reduce the pressure difference between the inside and outside of the sealing tube by supplementing the adjustment of the pressure of the pressure compensation chamber, thereby reducing the pressure on the sealing tube due to the operation of the filling gun and extending the service life of the sealing tube; and can adjust the pressure in the pressure compensation chamber according to the change of the volume of the pressure compensation chamber, thereby adapting to the movement of the valve stem to achieve precise control of the valve port, and reducing the influence of the working pressure of the charging gun on the control valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the three-dimensional structure of the filling gun;

[0039] Figure 2 Schematic diagram of the internal structure of the filling gun;

[0040] Figure 3 It is a partial cross-sectional structural diagram of a filling gun;

[0041] Figure 4 Schematic diagram of the sealing tube structure.

[0042] In the picture:

[0043] 10-lower straight pipe;

[0044] 20- three-way cavity; 21- second top plate; 22- second bottom plate;

[0045] 30 - pressure compensation chamber; 31 - first guide washer; 32 - second guide washer; 33 - gap; 35 - pressure compensation port; 36 - first top plate; 37 - first bottom plate;

[0046] 40-valve stem; 41-main rod; 42-connecting rod;

[0047] 50-valve head;

[0048] 60-filling tube;

[0049] 70-sealing tube; 71-locking ring; 72-inner steel ring; 73-outer steel ring;

[0050] 80-spring. DETAILED DESCRIPTION

[0051] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0053] like Figure 1-3 As shown, the charging gun provided by the present invention includes:

[0054] The lower straight tube 10 has a filling port at the bottom;

[0055] The three-way cavity 20 is connected to the lower straight pipe 10 at the bottom and connected to the filling pipe 60 on the side wall;

[0056] The pressure compensation chamber 30 is connected to the three-way chamber 20; the diaphragm chamber, the three-way chamber 20 and the lower straight tube 10 are connected to form;

[0057] The valve stem 40 includes a main stem 41 and a connecting rod 42. The connecting rod 42 is connected to the lower end of the main stem 41. The main stem 41 passes through the three-way cavity 20 and the pressure compensation cavity 30. The connecting rod 42 is located in the lower straight tube 10.

[0058] The valve head 50 is connected to the lower end of the connecting rod 42, and the valve head 50 can be sealed or opened with respect to the filling port of the lower straight pipe 10;

[0059] In which, the main rod 41 and the upper end of the pressure compensation chamber 30 are slidingly and sealedly connected through the first guide washer 31; a retractable sealing tube 70 is provided in the pressure compensation chamber 30, and the sealing tube 70 is sleeved on the main rod 41, the top of the sealing tube 70 is fixed and sealed to the outer wall of the main rod 41, and the bottom of the sealing tube 70 is clamped and sealed by the pressure compensation chamber 30 and the three-way chamber, so that the sealing tube divides the space in the pressure compensation chamber into two inner and outer chambers: a cylindrical second pressure chamber is formed by the main rod 41, the connecting rod 42, the lower straight tube 10 and the sealing tube, the second pressure chamber serves as a working chamber, and a cylindrical first pressure chamber is formed by the inner wall of the pressure compensation chamber 30, the sealing tube 70, the main rod 41 and the first guide washer 31, and the first pressure chamber is used to compensate for the pressure of the working chamber.

[0060] A pressure compensation port is provided on the pressure compensation chamber 30. When the volume of the first pressure chamber increases, pressure is added to the first pressure chamber through the pressure compensation port to reduce the pressure difference between the first pressure chamber and the second pressure chamber.

[0061] The pressure compensation port is equipped with a pressure valve. When the main rod 41 moves downward, pressure is added to the pressure compensation chamber 30 through the pressure valve. Alternatively, the pressure valve can be used to add and maintain pressure in the pressure compensation chamber 30 to prevent gas leakage. For example, when the maximum operating pressure of the working chamber is 1 MPa, the pressure in the pressure compensation chamber 30 can be increased to 0.5 MPa. This ensures that the pressure experienced by the sealing tube 70 in both operating and non-operating states is within ±0.5 MPa, significantly extending the service life of the sealing tube 70.

[0062] The gas filled into the pressure compensation chamber 30 is preferably nitrogen.

[0063] In particular: In this embodiment, when the valve stem 40 moves downward to open the valve port and the charging gun works, the pressure compensation chamber 30 is pressurized, so that the pressure of the first pressure chamber is greater than the pressure of the second pressure chamber, or the pressure difference between the first pressure chamber and the second pressure chamber is maintained within 0.1Mpa, so that the valve stem moves downward to control the opening of the valve port more labor-saving and more accurate, and can overcome the reaction of the working pressure on the valve stem sealing tube.

[0064] A second guide washer 32 is further provided on the top of the three-way cavity 20 . A pore 33 communicating with each other from top to bottom is provided on the second guide washer 32 to connect the sealing tube 70 with the three-way cavity 20 .

[0065] The sealing tube 70 is a bellows structure made of an elastic rubber material. Preferably, an inner steel ring 72 is positioned within the inner corner of the bellows' larger, convex ring, and an outer steel ring 73 is positioned within the outer corner of the bellows' smaller, concave ring. The inner steel ring 72 improves the sealing tube 70's ability to withstand external pressure and minimize deformation, while the outer steel ring 73 improves the sealing tube 70's ability to withstand internal pressure and minimize deformation. Together, the inner and outer steel rings 72 and 73 minimize deformation of the sealing tube 70 under pressure, preventing contact and friction with the main rod 41 or the inner wall of the pressure compensation chamber 30.

[0066] The main rod 41 is provided with a necking structure, i.e., a first section with a larger diameter and a second section with a smaller diameter, wherein the first section is slidingly connected to the first guide washer 31 and the second section is slidingly connected to the second guide washer 32; the upper end of the sealing tube 70 is connected to the first section, and the second section is located inside the sealing tube 70.

[0067] A locking ring 71 is provided at the upper end of the sealing tube 70 to lock and fix the sealing tube 70 and the main rod 41; optionally, a ring-cut locking groove is provided on the main rod 41 so that the locking ring can press the sealing tube into the locking groove, and when the pressure inside and outside the sealing tube 70 is increased, the sealing effect can be guaranteed.

[0068] The lower end of the sealing tube 70 is clamped and fixed by the pressure compensation chamber 30 and the three-way chamber 20 .

[0069] The pressure compensation chamber 30 is provided with a first top plate 36 at the top and a first bottom plate 37 at the bottom. The center hole of the first top plate 36 is provided with an annular stepped surface that accommodates the first guide washer 31. A spring 80 is sleeved onto the outside of the main rod 41 at the top of the pressure compensation chamber 30, and the bottom of the spring 80 presses against the first guide washer 31, thereby limiting the position of the first guide coil 31.

[0070] The top of the three-way cavity 20 is provided with a second top plate 21, and the bottom is provided with a second bottom plate 22. The second top plate 21 is provided with a through hole for accommodating the second guide washer 32; wherein, the first bottom plate 37 is docked with the second top plate 21, and the bottom of the sealing tube 70 is clamped and sealed. The sealing tube is clamped and sealed by clamping the first bottom plate and the second top plate, which can make the sealing effect of the sealing tube better and can keep the bottom of the sealing tube fixed when under pressure.

[0071] The filling gun provided by the present invention is provided with a pressure compensation chamber 30, and a retractable sealing tube 70 is provided therein. The upper end of the sealing tube 70 is sealedly connected to the main rod 41, and the lower end is sealedly connected to the inner wall of the pressure compensation chamber 30, so that when the main rod 41 moves downward to control the valve head 50, the upper end of the sealing tube 70 moves synchronously with the main rod 41 without generating sliding friction. At the same time, the pressure difference between the inside and outside of the sealing tube 70 is reduced through the pressure compensation port, thereby reducing the pressure that the sealing tube 70 is subjected to due to the operation of the filling gun and extending the service life of the sealing tube 70; in addition, since the pressure difference on both sides of the connection between the upper end of the sealing tube 70 and the main rod 41 is reduced, the possibility of material entering the pressure compensation chamber 30 is also reduced.

[0072] This embodiment also provides a method for controlling a charging gun, including:

[0073] Before opening the charging gun, obtain the charging pressure P1 of the charging gun;

[0074] The first pressure chamber in the pressure compensation chamber is filled with a first number of gas molecules n1, so that the pressure P2 in the first pressure chamber reaches 1 / 2 of the filling pressure P1. At this time, the sealing tube is in a stretched state, and the corresponding volume of the first pressure chamber is V1. Accordingly, it is necessary to ensure that the pressure bearing capacity of the sealing tube exceeds 1 / 2 of the filling pressure P1.

[0075] The control valve stem moves downward to open the valve port and increase the opening to the working state. This action process puts the sealing tube into a compressed state (the compressed state and the extended state in this embodiment are relative to each other; that is, the length of the sealing tube in the extended state is greater than the length of the sealing tube in the compressed state. In fact, either the extended state or the compressed state can be used, only the magnitude of the extension or compression is different). The volume of the first pressure chamber increases to V2. At this time, the second number of gas molecules n2 is filled into the pressure compensation chamber, raising the pressure in the first pressure chamber to 1 / 2 of the filling pressure P1. V1:V2=n1:(n1+n2). Since it is impossible to achieve the ideal state in actual operation, the actual application error of this formula is allowed within 10%. The purpose of this step is to maintain the pressure state of the first pressure chamber at 1 / 2 of the filling pressure P1, thereby ensuring that the pressure on the sealing tube is between ±P1 / 2, thereby reducing the pressure amplitude of the sealing tube by half.

[0076] Open the valve of the charging pipeline to connect the second pressure chamber with the charging pipeline, so that the material enters the second pressure chamber and is charged through the valve port. At this time, the pressure inside the second pressure chamber is P1. After being offset by P2 in the first pressure chamber, the sealed tube only withstands the pressure of P1 / 2. In other words, regardless of whether it is in working state or non-working state, the sealed tube only withstands the pressure of P1 / 2 (only the direction of the pressure is different).

[0077] When filling is completed, close the valve of the filling pipeline;

[0078] Blow air into the charging pipeline to clear the residual material in the second pressure chamber;

[0079] The pressure in the first pressure chamber is controlled to decrease, and then the valve stem is controlled to move upward, so that the pressure in the first pressure chamber during the upward movement of the valve stem is lower than 1 / 2 of the charging pressure.

[0080] The sealing tube between the first pressure chamber and the second pressure chamber is preferably a bellows;

[0081] Optionally, when the sealing tube is a bellows, an inner steel ring is preferably provided in the inner corner of the convex large ring of the bellows, and an outer steel ring is provided in the outer corner of the concave small ring of the bellows.

[0082] The volume parameters V1 and V2 are calculated by modeling the working state of the filling gun.

[0083] The pressure P2 of the first pressure chamber is obtained through a pressure gauge provided on the pressure compensation port of the pressure compensation chamber.

[0084] The control method of the charging gun provided by the present invention adopts a method of pre-pressurizing and maintaining the first pressure chamber, and supplements the pressure of the pressure compensation chamber to reduce the pressure difference between the inside and outside of the sealing tube, thereby reducing the pressure on the sealing tube due to the operation of the filling gun and extending the service life of the sealing tube; and can adjust the pressure in the pressure compensation chamber according to the change of the volume of the pressure compensation chamber, thereby adapting to the movement of the valve stem to achieve precise control of the valve port, and reducing the influence of the working pressure of the charging gun on the control valve.

[0085] The present invention provides a method for controlling a charging gun, comprising:

[0086] Control the valve stem to move downward, open the valve port and increase the opening of the valve port;

[0087] Open the valve of the charging pipeline to connect the second pressure chamber with the charging pipeline, so that the material enters the second pressure chamber and is charged through the valve port;

[0088] While opening the valve of the charging pipeline, the first pressure chamber in the pressure compensation chamber is pressurized to increase the pressure in the first pressure chamber, and the pressure difference between the first pressure chamber and the second pressure chamber is maintained within a preset range, for example, within ±0.1 MPa;

[0089] The pressure of the first pressure chamber and the pressure of the second pressure chamber are adjusted to a balanced state.

[0090] The control method of the charging gun provided by the present invention reduces the pressure difference between the inside and outside of the sealing tube by real-time pressure replenishment of the first pressure chamber, and reduces the pressure difference between the inside and outside of the sealing tube by supplementary adjustment of the pressure of the pressure compensation chamber, thereby reducing the pressure on the sealing tube due to the operation of the filling gun and extending the service life of the sealing tube; and can adjust the pressure in the pressure compensation chamber according to the change of the volume of the pressure compensation chamber, thereby adapting to the movement of the valve stem to achieve precise control of the valve port, and reducing the influence of the working pressure of the charging gun on the control valve.

[0091] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for controlling a charging gun, comprising: Before opening the charging gun, obtain the charging pressure P1 of the charging gun; The first pressure chamber in the pressure compensation chamber is filled with a first number of gas molecules n1, so that the pressure P2 in the first pressure chamber reaches 1 / 2 of the filling pressure P1. At this time, the sealing tube is in a stretched state, and the corresponding volume of the first pressure chamber is V1. The control valve stem moves downward to open the valve port and increase the opening to the working state. This action process puts the sealing tube into a compressed state, and the volume of the first pressure chamber increases to V2. At this time, the second number of molecules of gas n2 is filled into the pressure compensation chamber, so that the pressure of the first pressure chamber is increased to 1 / 2 of the charging pressure P1; V1:V2=n1:(n1+n2); Open the valve of the charging pipeline to connect the second pressure chamber with the charging pipeline, so that the material enters the second pressure chamber and is charged through the valve port; When filling is completed, close the valve of the filling pipeline; Blow air into the charging pipeline to clear the residual material in the second pressure chamber; Control the pressure in the first pressure chamber to decrease, and then control the valve stem to move upward, so that the pressure in the first pressure chamber during the upward movement of the valve stem is lower than 1 / 2 of the charging pressure; The filling guns include: Lower straight pipe with a filling port at the bottom; A three-way cavity, the bottom of which is connected to the lower straight pipe and the side wall of which is connected to the filling pipe; a pressure compensation chamber connected to the three-way chamber; The valve stem comprises a main stem and a connecting rod, wherein the connecting rod is connected to the lower end of the main stem, the main stem passes through the three-way cavity and the pressure compensation cavity, and the connecting rod is located in the lower straight tube; The valve head is connected to the lower end of the connecting rod, and the valve head can be sealed and connected to the filling port of the lower straight pipe or opened; In which, the main rod and the upper end of the pressure compensation chamber are slidingly and sealedly connected through a first guide washer; a retractable sealing tube is provided in the pressure compensation chamber, and the sealing tube is sleeved on the main rod, the top of the sealing tube is fixed and sealed to the outer wall of the main rod, and the bottom of the sealing tube is clamped and sealed between the inner wall of the pressure compensation chamber and the inner wall of the three-way chamber, so that the sealing tube divides the space in the pressure compensation chamber into two inner and outer chambers: a cylindrical second pressure chamber is formed by the main rod, the connecting rod, the lower straight tube and the sealing tube, the second pressure chamber serves as a working chamber, and a cylindrical first pressure chamber is formed by the inner wall of the pressure compensation chamber, the sealing tube, the main rod and the first guide washer, and the first pressure chamber is used to compensate for the pressure of the working chamber.

2. The control method according to claim 1, characterized in that: The sealing tube between the first pressure chamber and the second pressure chamber adopts a bellows; When the sealing tube is a bellows, an inner steel ring is provided in the inner corner of the convex large ring of the bellows, and an outer steel ring is provided in the outer corner of the concave small ring of the bellows.

3. The control method according to claim 1, characterized in that: The volume parameters V1 and V2 are calculated by modeling the working state of the filling gun; The pressure P2 of the first pressure chamber is obtained through a pressure gauge provided on the pressure compensation port of the pressure compensation chamber.

4. The control method according to claim 1, wherein: A second guide washer is further provided on the top of the three-way cavity. The second guide washer is provided with a hole communicating with each other up and down to connect the sealing tube and the three-way cavity.

5. The control method according to claim 1, characterized in that: The main rod is provided with a necking structure, namely a first section with a larger diameter and a second section with a smaller diameter, wherein the first section is slidingly connected to the first guide washer and the second section is slidingly connected to the second guide washer; the upper end of the sealing tube is connected to the first section, and the second section is located inside the sealing tube.

6. The control method according to claim 1, characterized in that: A locking ring is provided at the upper end of the sealing tube to lock and fix the sealing tube to the main rod; a locking groove with an annular cut is provided on the main rod to enable the locking ring to press the sealing tube into the locking groove; The lower end of the sealing tube is clamped and fixed by the pressure compensation cavity and the three-way cavity.

7. The control method according to claim 1, characterized in that: The pressure compensation chamber is provided with a first top plate on the top and a first bottom plate on the bottom. The center hole of the first top plate is provided with an annular step surface for accommodating a first guide washer. The top of the three-way cavity is provided with a second top plate, the bottom is provided with a second bottom plate, and the second top plate is provided with a through hole for accommodating the second guide washer; wherein the first bottom plate and the second top plate are butted together and clamp and seal the bottom of the sealing tube.

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