Single spring reset safety valve with large opening and assembling method thereof

Abstract

This invention discloses a single-spring reset safety valve capable of large opening and its assembly method. The valve body includes a bottom opening for a mud inlet and a side opening for a mud outlet. A hollow piston rod is installed inside the valve body. The hollow piston rod has a three-section structure, with a sliding groove and a cam groove on the middle cylindrical surface. An anti-rotation pad, a compression spring, and an anti-rotation pressure plate are fitted on the top cylinder. A positioning guide pin is installed on the side of the valve body, with its end inserted into the cam groove. A guide flange assembly and a piston seal ring are installed in the bottom inner hole of the valve body. The middle cylinder of the guide flange assembly is fixedly connected to the top support column by multiple circumferentially distributed ribs. A guide seal is installed on the top support column, with its outer wall tightly fitted against the inner wall of the bottom inner hole of the hollow piston rod. This invention employs a built-in single-spring structure, solving the problems of collision and uneven force distribution among multiple springs in existing spring reset safety valves with exposed double springs.

Description

Technical Field

[0001] This invention belongs to the field of petroleum equipment technology and relates to a single-spring reset safety valve capable of achieving a large opening degree and its assembly method. Background Technology

[0002] Currently, there are two main types of drilling pump venting safety valves: shear type and spring return type. Both safety valves are installed on the drilling pump outlet. When the drilling pump pressure exceeds the set value, the safety valve will open to create a venting channel at the drilling pump outlet, so as to prevent excessive pressure from damaging the drilling pump.

[0003] Both types of safety valves currently have some shortcomings. For example, the safety pin used in the shear pin type safety valve requires adjustment of its outer diameter each time based on strength tests, and there is a large gap between the safety pin, the shear pin plate, and the valve body after assembly. Therefore, the pressure setting of the shear pin type safety valve often differs significantly from the actual discharge pressure. On the other hand, the spring return type safety valve has a more complex internal structure, more components, and higher requirements for installation accuracy. At the same time, the safety valve has poor adaptability to transportation, installation, storage, and operating conditions. It is easy for the discharge accuracy of the safety valve to be seriously affected by the slight deformation of the exposed load spring or improper placement. Therefore, neither of these two types of safety valves is conducive to the safe, continuous, and efficient operation of mud pumps. Summary of the Invention

[0004] One objective of this invention is to provide a single-spring reset safety valve that can achieve a large opening, thereby solving the problem that the exposed double springs in existing spring reset safety valves will collide and the forces of multiple springs will be uncoordinated.

[0005] Another object of the present invention is to provide a method for assembling a single-spring reset safety valve that enables a large opening.

[0006] The first technical solution adopted in this invention is a single-spring reset safety valve capable of achieving a large opening degree, comprising a valve body with a three-way structure. The bottom opening is for a mud inlet, and the side opening is for a mud outlet. A hollow piston rod is installed inside the valve body. The hollow piston rod has a three-section structure, with a sliding groove and a cam groove on the side of the middle cylinder. An anti-rotation pad, a compression spring, and an anti-rotation pressure plate are sequentially fitted on the top cylinder. A positioning guide device is installed on the side of the valve body, including a positioning guide pin, the end of which is inserted into the cam groove. The valve body is slidably connected to the cam groove. A guide flange assembly and a piston seal ring are installed in the inner hole at the bottom of the valve body. The piston seal ring is located between the bottom end face of the hollow piston rod and the bottom of the mud outlet. The guide flange assembly is composed of a base plate, a middle cylinder and a top support column that are fixedly connected. The base plate is fixed to the valve body by screw B. The middle cylinder and the top support column are fixedly connected by multiple circumferentially distributed stiffeners. The gap between adjacent stiffeners is the mud channel. A guide seal is installed on the top support column. The outer wall of the guide seal is in close contact with the inner wall of the bottom inner hole of the hollow piston rod.

[0007] The valve body has an anti-rotation groove and a stepped surface A on its inner wall. An anti-rotation pad is installed on the stepped surface A. The anti-rotation pad is annular, with two inner anti-rotation teeth facing each other on its inner wall and an outer anti-rotation tooth A on its outer wall. A positioning step is provided on the top surface. The bottom of the compression spring is fitted onto the positioning step. The end of the outer anti-rotation tooth A is inserted into the anti-rotation groove and slidably connected to it. The inner anti-rotation teeth can slide in the groove. The valve body positioning hole is located in the middle of the stepped surface A. The top of the middle cylinder of the hollow piston rod is located in the valve body positioning hole. The diameter of the middle cylinder of the hollow piston rod is larger than the distance between the two inner anti-rotation teeth. Two stops are facing each other on the top surface of the middle cylinder of the hollow piston rod. The distance between the two stops is the same as the distance between the two inner anti-rotation teeth.

[0008] The valve body has an internal thread on the top of its inner wall. An adjusting nut is fitted on the top cylinder of the hollow piston rod and is connected to the internal thread. An observation window is provided on the side wall of the valve body, and a pressure scale is installed in the observation window. The anti-rotation pressure plate has a pointer insertion hole and an external anti-rotation tooth B on its side. A positioning boss is provided on the bottom surface. A guide hole is opened in the center of the anti-rotation pressure plate. A pointer is installed in the pointer insertion hole, with one end of the pointer inserted into the pointer insertion hole and the other end facing the pressure scale. The end of the external anti-rotation tooth B is inserted into the anti-rotation groove and is slidably connected to the anti-rotation groove. The top of the compression spring is fitted on the outside of the positioning boss.

[0009] The hollow piston rod has a reset plate and an oil cup installed at the top end. The inner holes of the middle cylinder and the top cylinder of the hollow piston rod are long and narrow holes. The bottom cylinder of the hollow piston rod is a thin-walled barrel structure. The inner hole diameter of the bottom cylinder is larger than the diameter of the long and narrow hole. The oil cup is connected to the long and narrow hole in the top cylinder.

[0010] A stepped surface B is provided on the inner wall of the valve body, and the piston sealing ring is located between the bottom surface of the stepped surface B and the top surface of the middle cylinder of the guide flange assembly.

[0011] The bottom cylindrical end of the hollow piston rod is inserted into the middle cylinder of the guide flange assembly and is slidably connected to the inner wall of the middle cylinder of the guide flange assembly. A sealing gland is installed on the top support column of the guide flange assembly. The sealing gland is threadedly connected to the top support column of the guide flange assembly, and the guide seal is located at the bottom of the sealing gland.

[0012] The cam groove is triangular in shape and is composed of straight grooves, flat grooves and inclined grooves connected together. The inclined groove is connected to the middle of the straight groove. The flat groove and the straight groove are shallow grooves with the same depth. The top of the inclined groove is a deep groove, and the bottom is a smooth transition structure from the deep groove to the shallow groove. The groove depth of the deep groove is greater than the groove depth of the shallow groove.

[0013] The positioning guide device also includes a telescopic spring, screw A and a pressure cap. A limit plate is provided in the middle of the positioning guide pin. The telescopic spring is sleeved on the end of the positioning guide pin away from the hollow piston rod. The pressure cap is fixed to the side wall of the valve body by screw A.

[0014] A protective cover is installed on the top of the valve body, and the protective cover is threaded to the outer wall of the valve body.

[0015] The second technical solution adopted in this invention is an assembly method for a single-spring reset safety valve capable of achieving a large opening degree, comprising the following steps: Step 1: Install the anti-rotation pad on the stepped surface A inside the valve body, so that the end of the outer anti-rotation tooth A of the anti-rotation pad is located in the anti-rotation groove. Then install the compression spring on the upper part of the anti-rotation pad, with the bottom of the compression spring fitted onto the positioning step. Install the anti-rotation pressure plate on the top of the compression spring, so that the top of the compression spring is fitted onto the outside of the positioning boss, and the end of the outer anti-rotation tooth B of the anti-rotation pressure plate is located in the anti-rotation groove. Step 2: Install the pointer in the pointer socket of the anti-rotation pressure plate through the observation window on the side wall of the valve body, and at the same time install the pressure scale in the observation window; Step 3: Install an adjusting nut on the top of the anti-rotation pressure plate and press the adjusting nut tightly against the upper surface of the anti-rotation pressure plate; Step 4: Install the hollow piston rod through the bottom opening of the valve body. First, insert the top cylindrical part of the hollow piston rod into the inner holes of the anti-rotation pad, compression spring, anti-rotation pressure plate and adjusting nut. Then, install the positioning guide device in the mounting holes on the side wall of the valve body. At the same time, rotate the hollow piston rod to insert the end of the positioning guide pin into the top of the inclined groove of the cam groove. Step 5: Install the guide seal and sealing gland at the top of the top support column of the guide flange assembly. Install the piston seal ring in the inner hole at the bottom of the valve body, so that the top surface of the piston seal ring is close to the bottom surface of step surface B. Then install the guide flange assembly in the inner hole at the bottom of the valve body, so that the top surface of the middle cylinder of the guide flange assembly presses against the bottom surface of the piston seal ring. At the same time, the guide seal and sealing gland are located in the inner hole at the bottom of the hollow piston rod. Finally, fix the guide flange assembly to the bottom of the valve body with screw B.

[0016] The beneficial effects of this invention are as follows: (1) By installing a hollow piston rod, anti-rotation pad, compression spring and anti-rotation pressure plate in the valve body, only one compression spring is needed. The built-in single spring structure not only solves the practical problems of the existing spring reset safety valve, such as the exposed double springs being easily bumped and the multiple springs being coordinated, which are subject to harsh working conditions, but also solves the problem of the existing shear pin type safety valve having a large discharge pressure error and the need to install shear pins after each discharge. Moreover, the internal pressure transmission chain and discharge principle of this safety valve are relatively simple. The pressure setting mechanism composed of adjusting nut, pressure scale and pointer can accurately set the pressure, which significantly improves the working condition adaptability of this single spring reset safety valve. (2) The hollow piston rod is a three-section structure. The middle cylindrical side is provided with a sliding groove and a cam groove. The cam groove is triangular and is composed of a straight groove, a flat groove and an oblique groove. A positioning guide device is installed on the side of the valve body. The end of the positioning guide pin is inserted into the cam groove and is slidably connected with the cam groove. A guide flange assembly and a piston sealing ring are installed in the inner hole at the bottom of the valve body. Under the action of high pressure mud, the hollow piston rod moves rapidly upward along the inner anti-rotation teeth of the anti-rotation pad, which causes the bottom of the hollow piston rod to separate from the piston sealing ring, thereby opening the channel between the mud inlet and outlet of the valve body to realize the release of high pressure mud. The safety valve is opened to a large degree by sliding the end of the positioning guide pin in the cam groove, which increases the fluid flow rate. (3) By installing a reset plate at the top end of the hollow piston rod, when a reset is required, the safety valve can be reset simply by pressing and rotating the reset plate. The operation is simple and easy to implement. Attached Figure Description

[0017] Figure 1 This is an assembly cross-sectional view of the single-spring reset safety valve of the present invention, which can achieve a large opening degree; Figure 2 This is a structural diagram of the hollow piston rod in the single-spring reset safety valve of the present invention, which can achieve a large opening degree; Figure 3 This is a structural diagram of the cam groove on the hollow piston rod of the single-spring reset safety valve that enables a large opening degree according to the present invention; Figure 4 This is a cross-sectional view of the guide flange assembly in the single-spring reset safety valve of the present invention, which enables a large opening degree. Figure 5 This is an exploded view of the guide flange assembly in the single-spring reset safety valve of the present invention, which enables a large opening degree. Figure 6 This is an exploded view of the single-spring reset safety valve of the present invention, which enables a large opening degree. Figure 7 This is a mid-section view of the single-spring reset safety valve of the present invention, which can achieve a large opening degree; Figure 8 This is a diagram showing the positional relationship between the hollow piston rod and the pressure scale in the single-spring reset safety valve of the present invention, which can achieve a large opening. Figure 9 This is a mid-section view of the compression spring, pointer, and adjusting nut in the single-spring reset safety valve of the present invention, which enables a large opening. Figure 10 This is an exploded view of the compression spring, pointer, and adjusting nut in the single-spring reset safety valve of the present invention, which enables a large opening. Figure 11 This is a cross-sectional view of the valve body in the single-spring reset safety valve of the present invention, which can achieve a large opening degree; Figure 12This is a structural diagram of the anti-rotation pad in the single-spring reset safety valve of the present invention, which enables a large opening degree; Figure 13 This is a structural diagram of the anti-rotation pressure plate in the single-spring reset safety valve of the present invention, which can achieve a large opening degree; Figure 14 This is a structural diagram of the positioning guide device in the single-spring reset safety valve of the present invention, which enables a large opening degree; Figure 15 This is an exploded view of the positioning guide device in the single-spring reset safety valve of the present invention, which enables a large opening.

[0018] In the diagram, 1. Valve body, 2. Hollow piston rod, 3. Positioning guide device, 4. Compression spring, 5. Pressure scale, 6. Pointer, 7. Adjusting nut, 8. Reset plate, 9. Protective cover, 10. Anti-rotation pressure plate, 11. Anti-rotation pad, 12. Guide flange assembly, 13. Piston seal ring, 14. Slide groove, 15. Cam groove, 16. Stop block, 17. Long narrow hole, 18. Positioning guide pin, 19. Telescopic spring, 20. Screw A, 2 1. Gland, 22. Anti-rotation groove, 23. Internal thread, 24. Sealing gland, 25. Guide seal, 26. Screw B, 27. Pointer hole, 28. Guide hole, 29. Internal anti-rotation tooth, 30. External anti-rotation tooth A, 31. Flat groove, 32. Straight groove, 33. Inclined groove, 34. Valve body positioning hole, 35. Mud outlet, 36. Step surface A, 37. Step surface B, 38. External anti-rotation tooth B, 39. Positioning step, 40. Positioning boss. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] Example 1 A single-spring return safety valve capable of achieving a large opening degree, see [link to relevant documentation]. Figure 1 and Figure 2 The valve body 1 is the outer shell of the safety valve. It has a three-way structure with a bottom opening for the mud inlet and a side opening for the mud outlet 35. A protective cover 9 is installed on the top of the valve body 1, threaded to the outer wall of the valve body 1. Inside the valve body 1 is a hollow piston rod 2, a three-section structure consisting of a top cylinder, a middle cylinder, and a bottom cylinder. The middle cylinder has two sliding grooves 14 and two cam grooves 15 on its side. The two sliding grooves 14 and cam grooves 15 are opposite each other. The sliding grooves 14 are axial straight grooves, and the cam grooves 15 are triangular, composed of a straight groove 32, a flat groove 31, and an inclined groove 33. The inclined groove 33 is connected to the middle of the straight groove 32. The flat groove 31 and the straight groove 32 are shallow grooves with the same depth. The top of the inclined groove 33 is a deep groove, and the bottom has a smooth transition from deep to shallow grooves. The depth of the deep groove is greater than the depth of the shallow groove. (See [reference]). Figure 3 .

[0021] An anti-rotation pad 11, a compression spring 4, and an anti-rotation pressure plate 10 are sequentially fitted onto the top cylinder of the hollow piston rod 2. A positioning guide device 3 is installed on the side of the valve body 1. The positioning guide device 3 includes a positioning guide pin 18. The end of the positioning guide pin 18 is inserted into the cam groove 15 and is slidably connected with the cam groove 15. A guide flange assembly 12 and a piston sealing ring 13 are installed in the inner hole at the bottom of the valve body 1. The piston sealing ring 13 is located between the bottom end face of the hollow piston rod 2 and the bottom of the mud outlet 35.

[0022] See Figure 4 and Figure 5 The guide flange assembly 12 is composed of a base plate, a middle cylinder and a top support column that are fixedly connected. The base plate is fixed to the valve body 1 by screws B26. The middle cylinder and the top support column are fixedly connected by multiple circumferentially distributed stiffeners. The gap between adjacent stiffeners is a mud channel. A guide seal 25 is installed on the top support column. The outer wall of the guide seal 25 is in close contact with the inner wall of the bottom inner hole of the hollow piston rod 2.

[0023] Example 2 A single-spring return safety valve capable of achieving a large opening degree, see [link to relevant documentation]. Figure 6 The system includes a valve body 1, which is a three-way valve with a bottom opening for a mud inlet and a side opening for a mud outlet 35. A hollow piston rod 2 is installed inside the valve body 1. The hollow piston rod 2 has a three-section structure, with a sliding groove 14 and a cam groove 15 on the side of the middle cylinder. An anti-rotation pad 11, a compression spring 4, and an anti-rotation pressure plate 10 are sequentially fitted onto the top cylinder. A positioning guide device 3 is installed on the side of the valve body 1, including a positioning guide pin 18. The end of the positioning guide pin 18 is inserted into the cam groove 15 and slidably connected to it. A guide flange assembly 12 and a piston seal ring 13 are installed in the bottom inner hole. The piston seal ring 13 is located between the bottom end face of the hollow piston rod 2 and the bottom of the mud outlet 35. The guide flange assembly 12 is composed of a base plate, a middle cylinder and a top support column fixedly connected. The base plate is fixedly connected to the valve body 1 by screws B26. The middle cylinder and the top support column are fixedly connected by multiple circumferentially distributed stiffeners. The gap between adjacent stiffeners is the mud channel. A guide seal 25 is installed on the top support column. The outer wall of the guide seal 25 is in close contact with the inner wall of the bottom inner hole of the hollow piston rod 2.

[0024] The cam groove 15 is triangular in shape and is composed of a straight groove 32, a flat groove 31 and an inclined groove 33 connected together. The inclined groove 33 is connected to the middle of the straight groove 32. The flat groove 31 and the straight groove 32 are shallow grooves with the same depth. The top of the inclined groove 33 is a deep groove and the bottom is a smooth transition structure from the deep groove to the shallow groove. The groove depth of the deep groove is greater than the groove depth of the shallow groove.

[0025] The valve body 1 has an anti-rotation groove 22 and a stepped surface A36 on its inner wall. An anti-rotation pad 11 is installed on the stepped surface A36. The anti-rotation pad 11 is annular, with two inner anti-rotation teeth 29 arranged opposite each other on its inner wall and outer anti-rotation teeth A30 arranged on its outer wall. A positioning step 39 is provided on its top surface. The bottom of the compression spring 4 is fitted onto the positioning step 39. The end of the outer anti-rotation tooth A30 is inserted into the anti-rotation groove 22 and is slidably connected to the anti-rotation groove 22. The inner anti-rotation teeth 29 can slide in the slide groove 14. When the anti-rotation pad is inside the valve body... When the valve body moves up and down axially, the outer anti-rotation tooth A30 and the inner anti-rotation tooth will block the anti-rotation pad from rotating relative to the circumference of the valve body; the middle of the stepped surface A36 is the valve body positioning hole 34, the top of the middle cylinder of the hollow piston rod 2 is located in the valve body positioning hole 34, the diameter of the middle cylinder of the hollow piston rod 2 is larger than the distance between the two inner anti-rotation teeth 29, and two stops 16 are arranged opposite each other on the top surface of the middle cylinder of the hollow piston rod 2, the distance between the two stops 16 is the same as the distance between the two inner anti-rotation teeth 29.

[0026] Example 3 A single-spring return safety valve capable of achieving a large opening degree, see [link to relevant documentation]. Figure 7 The system includes a valve body 1, which is a three-way valve with a bottom opening for a mud inlet and a side opening for a mud outlet 35. A hollow piston rod 2 is installed inside the valve body 1. The hollow piston rod 2 has a three-section structure, with a sliding groove 14 and a cam groove 15 on the side of the middle cylinder. An anti-rotation pad 11, a compression spring 4, and an anti-rotation pressure plate 10 are sequentially fitted onto the top cylinder. A positioning guide device 3 is installed on the side of the valve body 1, including a positioning guide pin 18. The end of the positioning guide pin 18 is inserted into the cam groove 15 and slidably connected to it. A guide flange assembly 12 and a piston seal ring 13 are installed in the bottom inner hole. The piston seal ring 13 is located between the bottom end face of the hollow piston rod 2 and the bottom of the mud outlet 35. The guide flange assembly 12 is composed of a base plate, a middle cylinder and a top support column fixedly connected. The base plate is fixedly connected to the valve body 1 by screws B26. The middle cylinder and the top support column are fixedly connected by multiple circumferentially distributed stiffeners. The gap between adjacent stiffeners is the mud channel. A guide seal 25 is installed on the top support column. The outer wall of the guide seal 25 is in close contact with the inner wall of the bottom inner hole of the hollow piston rod 2.

[0027] The valve body 1 has an anti-rotation groove 22 and a stepped surface A36 on its inner wall. An anti-rotation pad 11 is installed on the stepped surface A36. The anti-rotation pad 11 is annular. Two inner anti-rotation teeth 29 are arranged opposite each other on the inner wall. An outer anti-rotation tooth A30 is arranged on the outer wall. A positioning step 39 is arranged on the top surface. The bottom of the compression spring 4 is fitted onto the positioning step 39. The end of the outer anti-rotation tooth A30 is inserted into the anti-rotation groove 22 and is slidably connected with the anti-rotation groove 22. The inner anti-rotation teeth 29 can slide in the slide groove 14. The valve body positioning hole 34 is located in the middle of the stepped surface A36. The top of the middle cylinder of the hollow piston rod 2 is located in the valve body positioning hole 34. The diameter of the middle cylinder of the hollow piston rod 2 is larger than the distance between the two inner anti-rotation teeth 29. Two stops 16 are arranged opposite each other on the top surface of the middle cylinder of the hollow piston rod 2. The distance between the two stops 16 is the same as the distance between the two inner anti-rotation teeth 29.

[0028] The two stops 16 on the hollow piston rod 2 have the same function as the cam groove. They can be used to position the two inner anti-rotation teeth 29 inside the anti-rotation pad 11 in the circumferential direction to ensure that the contact area between the lower end face of the inner anti-rotation teeth 29 of the anti-rotation pad 11 and the middle cylindrical end face of the hollow piston rod 2 remains unchanged after each reset, thereby ensuring that the hollow piston rod 2 moves the same distance to the discharge point each time.

[0029] See Figure 8 and Figure 9 The valve body 1 has an internal thread 23 on its inner wall. An adjusting nut 7 is fitted onto the top cylinder of the hollow piston rod 2, connecting to the internal thread 23. An observation window is provided on the side wall of the valve body 1, housing a pressure scale 5. The anti-rotation plate 10 has a pointer insertion hole 27 and an external anti-rotation tooth B38 on its side, and a positioning boss 40 on its bottom surface. A guide hole 28 is provided in the center of the anti-rotation plate 10, providing radial support and axial guidance for the hollow piston rod. A pointer 6 is installed in the pointer insertion hole 27, with one end inserted into the hole and the other end facing the pressure scale 5. The end of the external anti-rotation tooth B38 is inserted into the anti-rotation groove 22, slidingly connected to it. The top of the compression spring 4 is fitted onto the outside of the positioning boss 40. Figure 10 .

[0030] The compression of the spring can be adjusted by adjusting the nut. Since the anti-rotation pad installed at the bottom does not move downward relative to the valve body, the anti-rotation pressure plate installed at the top will cause the pointer to move up and down, indicating different pressure values ​​on the pressure scale. At the same time, since the anti-rotation pressure plate is also designed with the same external anti-rotation teeth as the anti-rotation pad, the anti-rotation pressure plate will not rotate relative to the valve body when the adjusting nut is rotated. This ensures that the compression spring is not subjected to additional rotational torque and that the pointer always moves up and down without rotating.

[0031] Example 4 A single-spring reset safety valve capable of large opening includes a valve body 1, which is a three-way structure with a bottom opening for a mud inlet and a side opening for a mud outlet 35. A hollow piston rod 2 is installed inside the valve body 1. The hollow piston rod 2 is a three-section structure, with a sliding groove 14 and a cam groove 15 on the side of the middle cylindrical section. The cam groove 15 is triangular and is composed of a straight groove 32, a flat groove 31, and an inclined groove 33. The inclined groove 33 is connected to the middle of the straight groove 32. The flat groove 31 and the straight groove 32 are shallow grooves with the same depth. The top of the inclined groove 33 is a deep groove, and the bottom is a smooth transition structure from the deep groove to the shallow groove. The depth of the deep groove is greater than the depth of the shallow groove.

[0032] An anti-rotation pad 11, a compression spring 4, and an anti-rotation pressure plate 10 are sequentially fitted onto the top cylinder of the hollow piston rod 2. A positioning guide device 3 is installed on the side of the valve body 1. The positioning guide device 3 includes a positioning guide pin 18, the end of which is inserted into the cam groove 15 and slidably connected with the cam groove 15. A guide flange assembly 12 and a piston sealing ring 13 are installed in the bottom inner hole of the valve body 1. The piston sealing ring 13 is located between the bottom end face of the hollow piston rod 2 and the bottom of the mud outlet 35. The guide flange assembly 12 is composed of a base plate, a middle cylinder, and a top support column that are fixedly connected. The base plate is fixedly connected to the valve body 1 by screws B26. The middle cylinder and the top support column are fixedly connected by multiple circumferentially distributed ribs. The gap between adjacent ribs is a mud channel. A guide seal 25 is installed on the top support column. The outer wall of the guide seal 25 is tightly attached to the inner wall of the bottom inner hole of the hollow piston rod 2, which has a supporting and guiding function.

[0033] See Figure 11 and Figure 12 The valve body 1 has an anti-rotation groove 22 and a stepped surface A36 on its inner wall. An anti-rotation pad 11 is installed on the stepped surface A36. The anti-rotation pad 11 is annular. Two inner anti-rotation teeth 29 are arranged opposite each other on the inner wall. An outer anti-rotation tooth A30 is arranged on the outer wall. A positioning step 39 is arranged on the top surface. The bottom of the compression spring 4 is fitted on the positioning step 39. The end of the outer anti-rotation tooth A30 is inserted into the anti-rotation groove 22 and is slidably connected with the anti-rotation groove 22. The inner anti-rotation teeth 29 can slide in the slide groove 14. The valve body positioning hole 34 is located in the middle of the stepped surface A36. The top of the middle cylinder of the hollow piston rod 2 is located in the valve body positioning hole 34. The diameter of the middle cylinder of the hollow piston rod 2 is larger than the distance between the two inner anti-rotation teeth 29. Two stops 16 are arranged opposite each other on the top surface of the middle cylinder of the hollow piston rod 2. The distance between the two stops 16 is the same as the distance between the two inner anti-rotation teeth 29.

[0034] See Figure 13The valve body 1 has an internal thread 23 on the top of its inner wall. An adjusting nut 7 is fitted on the top cylinder of the hollow piston rod 2. The adjusting nut 7 is connected to the internal thread 23. An observation window is provided on the side wall of the valve body 1. A pressure scale 5 is installed in the observation window. The anti-rotation pressure plate 10 has a pointer insertion hole 27 and an external anti-rotation tooth B38 on its side. A positioning boss 40 is provided on its bottom surface. A guide hole 28 is opened in the center of the anti-rotation pressure plate 10. A pointer 6 is installed in the pointer insertion hole 27. One end of the pointer 6 is inserted into the pointer insertion hole 27, and the other end is facing the pressure scale 5. The end of the external anti-rotation tooth B38 is inserted into the anti-rotation groove 22 and is slidably connected to the anti-rotation groove 22. The top of the compression spring 4 is fitted on the outside of the positioning boss 40.

[0035] The hollow piston rod 2 has a reset plate 8 and an oil cup installed at its top end. The inner holes of the middle cylinder and the top cylinder of the hollow piston rod 2 are long narrow holes 17. The bottom cylinder of the hollow piston rod 2 is a thin-walled barrel structure. The inner hole diameter of the bottom cylinder is larger than the diameter of the long narrow hole 17. The oil cup is connected to the long narrow hole 17 in the top cylinder. Lubricating oil is added to the long narrow hole 17 through the oil cup to lubricate the guide seal at the top of the guide flange assembly.

[0036] When the hollow piston rod moves to the upper part, pressing the reset plate will cause the sliding groove of the hollow piston rod to move downward along the inner anti-rotation teeth of the anti-rotation pad. At the same time, the positioning guide pin slides in the cam groove of the hollow piston rod. When the positioning guide pin slides to the end of the cam groove, the sliding groove of the hollow piston rod disengages from the inner anti-rotation teeth of the anti-rotation pad. At this time, rotating the reset plate will cause the flat groove in the cam groove to rotate along the positioning guide pin, and finally make the positioning guide pin positioned in the deep groove (i.e., the top of the inclined groove) of the outer cylindrical surface cam groove of the hollow piston rod, so as to prevent the reverse rotation of the hollow piston rod and restrict the hollow piston rod to move upward along the inclined groove of the cam groove.

[0037] A stepped surface B37 is provided on the inner wall of the valve body 1. The piston sealing ring 13 is located between the bottom surface of the stepped surface B37 and the top surface of the middle cylinder of the guide flange assembly 12. The bottom cylindrical end of the hollow piston rod 2 is inserted into the middle cylinder of the guide flange assembly 12 and is slidably connected to the inner wall of the middle cylinder of the guide flange assembly 12. A sealing gland 24 is installed on the top support column of the guide flange assembly 12. The sealing gland 24 is threadedly connected to the top support column of the guide flange assembly 12. The guide seal 25 is located at the bottom of the sealing gland 24.

[0038] Example 5 A single-spring return safety valve capable of achieving a large opening degree, see [link to relevant documentation]. Figure 1The system includes a valve body 1, which is a three-way valve with a bottom opening for the mud inlet and a side opening for the mud outlet 35. A protective cover 9 is installed on the top of the valve body 1, and the protective cover 9 is threaded to the outer wall of the valve body 1. A hollow piston rod 2 is installed inside the valve body 1. The hollow piston rod 2 is a three-section structure. A sliding groove 14 and a cam groove 15 are opened on the side of the middle cylindrical section. The cam groove 15 is triangular and is composed of a straight groove 32, a flat groove 31, and an inclined groove 33. The inclined groove 33 is connected to the middle of the straight groove 32. The flat groove 31 and the straight groove 32 are shallow grooves with the same depth. The top of the inclined groove 33 is a deep groove, and the bottom is a smooth transition structure from the deep groove to the shallow groove. The depth of the deep groove is greater than the depth of the shallow groove.

[0039] An anti-rotation pad 11, a compression spring 4, and an anti-rotation pressure plate 10 are sequentially fitted onto the top cylinder of the hollow piston rod 2. A positioning guide device 3 is installed on the side of the valve body 1. The positioning guide device 3 includes a positioning guide pin 18. The end of the positioning guide pin 18 is inserted into the cam groove 15 and is slidably connected with the cam groove 15. A guide flange assembly 12 and a piston sealing ring 13 are installed in the bottom inner hole of the valve body 1. The piston sealing ring 13 is located between the bottom end face of the hollow piston rod 2 and the bottom of the mud outlet 35. The guide flange assembly 12 is composed of a base plate, a middle cylinder, and a top support column that are fixedly connected. The base plate is fixedly connected to the valve body 1 by screws B26. The middle cylinder and the top support column are fixedly connected by multiple circumferentially distributed ribs. The gap between adjacent ribs is a mud channel. A guide seal 25 is installed on the top support column. The outer wall of the guide seal 25 is tightly attached to the inner wall of the bottom inner hole of the hollow piston rod 2.

[0040] When the end of the positioning guide pin is located in the inclined groove 33, the hollow piston rod 2 will rotate around its axis relative to the anti-rotation pad 11 while moving upward. When the hollow piston rod 2 moves up a certain distance and rotates a certain angle, the inner anti-rotation teeth 29 of the anti-rotation pad 11 will align with the slide groove 14 of the hollow piston rod 2. Due to the action of the high-pressure mud at the bottom of the hollow piston rod 2 and the fact that the inner anti-rotation teeth 29 of the anti-rotation pad 11 have disengaged from the upper end face of the slide groove 14 of the hollow piston rod 2 and align with the slide groove 14 of the hollow piston rod 2, the hollow piston rod 2 will move upward rapidly along the slide groove 14. At the same time, the lower part of the hollow piston rod 2 will disengage from the piston sealing ring 13, thereby opening the channel between the mud inlet and outlet of the valve body to realize the release of high-pressure mud.

[0041] The valve body 1 has an anti-rotation groove 22 and a stepped surface A36 on its inner wall. An anti-rotation pad 11 is installed on the stepped surface A36. The anti-rotation pad 11 is annular. Two inner anti-rotation teeth 29 are arranged opposite each other on the inner wall. An outer anti-rotation tooth A30 is arranged on the outer wall. A positioning step 39 is arranged on the top surface. The bottom of the compression spring 4 is fitted onto the positioning step 39. The end of the outer anti-rotation tooth A30 is inserted into the anti-rotation groove 22 and is slidably connected with the anti-rotation groove 22. The inner anti-rotation teeth 29 can slide in the slide groove 14. The valve body positioning hole 34 is located in the middle of the stepped surface A36. The top of the middle cylinder of the hollow piston rod 2 is located in the valve body positioning hole 34. The diameter of the middle cylinder of the hollow piston rod 2 is larger than the distance between the two inner anti-rotation teeth 29. Two stops 16 are arranged opposite each other on the top surface of the middle cylinder of the hollow piston rod 2. The distance between the two stops 16 is the same as the distance between the two inner anti-rotation teeth 29.

[0042] The valve body 1 has an internal thread 23 on the top of its inner wall. An adjusting nut 7 is fitted on the top cylinder of the hollow piston rod 2. The adjusting nut 7 is connected to the internal thread 23. An observation window is provided on the side wall of the valve body 1. A pressure scale 5 is installed in the observation window. A pointer insertion hole 27 and an external anti-rotation tooth B38 are provided on the side of the anti-rotation pressure plate 10. A positioning boss 40 is provided on the bottom surface. A guide hole 28 is opened in the center of the anti-rotation pressure plate 10. A pointer 6 is installed in the pointer insertion hole 27. One end of the pointer 6 is inserted into the pointer insertion hole 27, and the other end is facing the pressure scale 5. The end of the external anti-rotation tooth B38 is inserted into the anti-rotation groove 22 and is slidably connected to the anti-rotation groove 22. The top of the compression spring 4 is fitted on the outside of the positioning boss 40.

[0043] A reset plate 8 and an oil cup are installed at the top end of the hollow piston rod 2. The inner holes of the middle cylinder and the top cylinder of the hollow piston rod 2 are elongated narrow holes 17. The bottom cylinder of the hollow piston rod 2 has a thin-walled barrel structure, and the inner hole diameter of the bottom cylinder is larger than the diameter of the elongated narrow hole 17. The oil cup is connected to the elongated narrow hole 17 in the top cylinder. A stepped surface B37 is provided on the inner wall of the valve body 1. The piston sealing ring 13 is located between the bottom surface of the stepped surface B37 and the top surface of the middle cylinder of the guide flange assembly 12. The bottom cylindrical end of the hollow piston rod 2 is inserted into the middle cylinder of the guide flange assembly 12 and is slidably connected to the inner wall of the middle cylinder of the guide flange assembly 12. A sealing gland 24 is installed on the top support column of the guide flange assembly 12. The sealing gland 24 is threadedly connected to the top support column of the guide flange assembly 12. The guide seal 25 is located at the bottom of the sealing gland 24.

[0044] See Figure 14 and Figure 15 The positioning guide device 3 also includes a telescopic spring 19, a screw A20 and a pressure cap 21. A limit plate is provided in the middle of the positioning guide pin 18. The telescopic spring 19 is sleeved on the end of the positioning guide pin 18 away from the hollow piston rod 2. The pressure cap 21 is fixed to the side wall of the valve body 1 by the screw A20.

[0045] The end of the positioning guide pin is always inserted into the cam groove of the hollow piston rod under the action of the telescopic spring, and also plays a circumferential positioning role.

[0046] Example 6 An assembly method for a single-spring return safety valve capable of achieving a large opening degree includes the following steps: Step 1: Install the anti-rotation pad 11 on the stepped surface A36 inside the valve body 1, so that the end of the outer anti-rotation tooth A30 of the anti-rotation pad 11 is located in the anti-rotation groove 22. This ensures that the anti-rotation pad 11 can only move upward along the two anti-rotation grooves inside the valve body 1 and cannot rotate. Then, install the compression spring 4 on the upper part of the anti-rotation pad 11. The bottom of the compression spring 4 is fitted on the positioning step 39. Install the anti-rotation pressure plate 10 on the top of the compression spring 4, so that the top of the compression spring 4 is fitted on the outside of the positioning boss 40 to prevent the radial movement of the compression spring 4, and so that the end of the outer anti-rotation tooth B38 of the anti-rotation pressure plate 10 is located in the anti-rotation groove 22. Step 2: Install pointer 6 in pointer socket 27 of anti-rotation pressure plate 10 through observation window on side wall of valve body 1, and install pressure scale 5 in observation window at the same time; since anti-rotation pressure plate 10 can only move up and down and cannot rotate in valve body 1, when pressure is applied to the installed anti-rotation pressure plate 10, pointer 6 can move up and down and point to the pressure value on pressure scale 5. Step 3: Install the adjusting nut 7 on the top of the anti-rotation pressure plate 10. The adjusting nut 7 presses against the upper surface of the anti-rotation pressure plate 10. Since the outer anti-rotation tooth B of the anti-rotation pressure plate 10 ensures that it can only move up and down along the inside of the valve body 1 without rotating, the adjusting nut 7 will not cause additional torque to the compression spring 4 when it rotates. This ensures that the compression spring 4 has good linear mechanical properties under the pressure of the anti-rotation pressure plate 10. At this point, the pressure setting and adjustment mechanism of the safety valve is installed. Step 4: Install the hollow piston rod 2 through the bottom opening of the valve body 1. First, insert the top cylindrical part of the hollow piston rod 2 into the inner hole of the anti-rotation pad 11, the compression spring 4, the anti-rotation pressure plate 10, and the adjusting nut 7. The guide hole in the center of the anti-rotation pressure plate 10 cooperates with the top cylindrical surface of the hollow piston rod to provide support and guidance. Then, install the two positioning guide devices 3 in the mounting holes on both sides of the valve body 1 respectively. At the same time, rotate the hollow piston rod 2 to insert the end of the positioning guide pin 18 into the top of the inclined groove of the cam groove 15. In this way, the positioning guide pin of the positioning guide device 3 restricts the rotation and axial movement range of the hollow piston rod 2. Especially when the end of the positioning guide pin 18 is located in the inclined groove of the cam groove, the hollow piston rod 2 can only rotate and move upward along the inclined groove of its outer cylindrical surface under the guidance of the positioning guide pin 18, and then smoothly transition to the straight groove of the cam groove. This prevents the hollow piston rod 2 from rotating in the opposite direction under the guidance of the positioning guide pin 18. Meanwhile, when the positioning guide pin 18 of the positioning guide device 3 is located at the top of the inclined groove of the cam groove 15, the middle cylindrical surface of the hollow piston rod 2 cooperates with the positioning hole 34 and performs radial positioning on it, and the top surface of the middle outer cylinder of the hollow piston rod 2 cooperates with the lower plane of the inner anti-rotation tooth 29 of the anti-rotation pad 11. At this time, the inner anti-rotation tooth 29 of the anti-rotation pad 11 and the sliding groove 14 of the hollow piston rod 2 are completely misaligned. When the high-pressure mud at the lower part of the hollow piston rod 2 applies pressure to it and pushes the hollow piston rod 2 upward, the hollow piston rod 2, guided by the positioning guide pin 18 of the positioning guide device 3, first moves upward along the inclined groove of the cam groove 15. At the same time, the top surface of the outer cylinder in the middle of the hollow piston rod 2 and the anti-rotation pad 11 rotate relative to each other. When the hollow piston rod 2 moves to the straight groove at the lower part of the cam groove 15 under the guidance of the positioning guide pin 18, the sliding groove 14 of the hollow piston rod 2 is just aligned with the inner anti-rotation tooth 29 of the anti-rotation pad 11. The lower surface of the inner anti-rotation tooth 29 of the anti-rotation pad 11 loses its blocking effect on the top surface of the outer cylinder in the middle of the hollow piston rod 2. At this time, under the action of the high-pressure mud, the hollow piston rod 2 will move upward rapidly along the inner anti-rotation tooth 29 of the anti-rotation pad 11, thereby causing the lower part of the hollow piston rod 2 to separate from the piston sealing ring 13, thus opening the channel between the mud inlet and outlet of the valve body to realize the release of high-pressure mud.

[0047] Step 5: Install the guide seal 25 and sealing gland 24 on the top support column of the guide flange assembly 12. Install the piston seal ring 13 in the inner hole at the bottom of the valve body 1, so that the top surface of the piston seal ring 13 is close to the bottom surface of the step surface B37. Then install the guide flange assembly 12 in the inner hole at the bottom of the valve body 1, so that the top surface of the middle cylinder of the guide flange assembly 12 presses against the bottom surface of the piston seal ring 13. At the same time, the guide seal 25 and sealing gland 24 are both located in the bottom inner hole of the hollow piston rod 2, which plays a role in positioning, supporting, guiding and sealing the hollow piston rod 2, so as to prevent the lower part of the hollow piston rod 2 from deviating when it separates from the piston seal ring 13. In addition, due to the top structure of the guide flange assembly 12, the limited pressure area of ​​the high pressure mud acting on the lower part of the hollow piston rod 2 is only the circular area at the bottom of the hollow piston rod 2. Thus, the pressure of the mud on the hollow piston rod 2 is relatively small, and the force and specifications of the compression spring 4 will not be too large. This is also beneficial to the setting and adjustment of the safety valve pressure.

[0048] Step 6: Secure the guide flange assembly 12 to the bottom of the valve body 1 using screw B26.

[0049] When using the single-spring reset safety valve of this invention, the axial displacement and rotation angle generated when the hollow piston rod 2 moves from the top of the inclined groove in the cam groove 15 to the lowest point of the inclined groove under the guidance of the positioning guide pin 18 remain unchanged. At this time, the sliding groove of the hollow piston rod 2 is just aligned with the inner anti-rotation tooth 29 of the anti-rotation pad. At the same time, the compression amount of the compression spring 4 remains unchanged when the hollow piston rod 2 moves upward. In this way, the compression spring 4 can be adjusted to different axial positions by adjusting the adjusting nut 7. Consequently, the anti-rotation pressure plate and the pointer 6 will also point to different pressure values. When high-pressure mud... When the set pressure value is reached, the hollow piston rod 2 will be pushed up a fixed distance. When the groove of the hollow piston rod 2 is aligned with the inner anti-rotation tooth 29 of the anti-rotation pad 11, the inner anti-rotation tooth 29 of the anti-rotation pad 11 loses its blocking effect on the hollow piston rod 2. Thus, under the action of high-pressure mud, the hollow piston rod 2 will quickly separate from the piston sealing ring 13 and move up a distance to open the channel between the mud inlet and outlet of the valve body 1 to achieve the purpose of releasing high-pressure mud. At the same time, the positioning guide pin 18 of the positioning guide device 3 is located at the lowest point of the cam groove 15.

[0050] When the safety valve of this invention needs to be reset, remove the protective cover 9, press the reset plate 8 to make the hollow piston rod 2 move downward along the straight groove of its cam groove 15 until the positioning guide pin reaches the top of the straight groove. At this time, the sliding groove 14 of the hollow piston rod 2 is completely disengaged from the inner anti-rotation tooth 29 of the anti-rotation pad 11 and the inner anti-rotation tooth 29 of the anti-rotation pad 11 no longer interferes with the rotation of the hollow piston rod 2. Then rotate the reset plate 8 to make the positioning guide pin 18 of the positioning guide device 3 move to the deep groove at the top of the inclined groove of the cam groove 15. At the same time, the outer cylindrical surface of the lower part of the hollow piston rod 2 cooperates with the piston sealing ring 13 at the lower part and plays a sealing role. Thus, the reset operation of the safety valve is completed.

Claims

1. A single spring reset safety valve capable of large opening, characterized in that, The valve body (1) is a three-way valve with a bottom opening for mud inlet and a side opening for mud outlet (35). A hollow piston rod (2) is installed inside the valve body (1). The hollow piston rod (2) is a three-section structure with a sliding groove (14) and a cam groove (15) on the side of the middle cylinder. An anti-rotation pad (11), a compression spring (4), and an anti-rotation pressure plate (10) are sequentially fitted on the top cylinder. A positioning guide device (3) is installed on the side of the valve body (1). The positioning guide device (3) includes a positioning guide pin (18). The end of the positioning guide pin (18) is inserted into the cam groove (15) and slides with the cam groove (15). The valve body (1) is connected to a guide flange assembly (12) and a piston seal ring (13) installed in the bottom inner hole. The piston seal ring (13) is located between the bottom end face of the hollow piston rod (2) and the bottom of the mud outlet (35). The guide flange assembly (12) is composed of a base plate, a middle cylinder and a top support column. The base plate is connected and fixed to the valve body (1) by screw B (26). The middle cylinder and the top support column are fixedly connected by multiple circumferentially distributed stiffeners. The gap between adjacent stiffeners is the mud channel. A guide seal (25) is installed on the top support column. The outer wall of the guide seal (25) is close to the inner wall of the bottom inner hole of the hollow piston rod (2).

2. The single spring reset safety valve of claim 1, wherein, The valve body (1) has an anti-rotation groove (22) and a step surface A (36) on its inner wall. An anti-rotation pad (11) is installed on the step surface A (36). The anti-rotation pad (11) is annular. Two inner anti-rotation teeth (29) are arranged opposite each other on the inner wall. An outer anti-rotation tooth A (30) is arranged on the outer wall. A positioning step (39) is arranged on the top surface. The bottom of the compression spring (4) is fitted on the positioning step (39). The end of the outer anti-rotation tooth A (30) is inserted into the anti-rotation groove (22) and slides with the anti-rotation groove (22). The moving connection allows the inner anti-rotation teeth (29) to slide in the slide groove (14). The middle of the stepped surface A (36) is the valve body positioning hole (34). The top of the middle cylinder of the hollow piston rod (2) is located in the valve body positioning hole (34). The diameter of the middle cylinder of the hollow piston rod (2) is greater than the distance between the two inner anti-rotation teeth (29). Two blocks (16) are arranged opposite each other on the top surface of the middle cylinder of the hollow piston rod (2). The distance between the two blocks (16) is the same as the distance between the two inner anti-rotation teeth (29).

3. The single spring reset safety valve of claim 2, wherein, The valve body (1) has an internal thread (23) on the top of its inner wall. An adjusting nut (7) is fitted on the top cylinder of the hollow piston rod (2). The adjusting nut (7) is connected to the internal thread (23). An observation window is provided on the side wall of the valve body (1). A pressure scale (5) is installed in the observation window. A pointer insertion hole (27) and an external anti-rotation tooth B (38) are provided on the side of the anti-rotation pressure plate (10). A positioning boss (40) is provided on the bottom surface. A guide hole (28) is opened in the center of the anti-rotation pressure plate (10). A pointer (6) is installed in the pointer insertion hole (27). One end of the pointer (6) is inserted into the pointer insertion hole (27), and the other end is facing the pressure scale (5). The end of the external anti-rotation tooth B (38) is inserted into the anti-rotation groove (22) and is slidably connected to the anti-rotation groove (22). The top of the compression spring (4) is fitted on the outside of the positioning boss (40).

4. The single spring reset safety valve of claim 3, wherein, The hollow piston rod (2) is equipped with a reset plate (8) and an oil cup at its top end. The inner holes of the middle cylinder and the top cylinder of the hollow piston rod (2) are long narrow holes (17). The bottom cylinder of the hollow piston rod (2) is a thin-walled barrel structure. The inner hole diameter of the bottom cylinder is larger than the diameter of the long narrow hole (17). The oil cup is connected to the long narrow hole (17) in the top cylinder.

5. The single spring reset safety valve of claim 4, wherein, The valve body (1) has a stepped surface B (37) on its inner wall, and the piston sealing ring (13) is located between the bottom surface of the stepped surface B (37) and the top surface of the middle cylinder of the guide flange assembly (12).

6. The single spring reset safety valve of claim 5, wherein, The bottom cylindrical end of the hollow piston rod (2) is inserted into the middle cylinder of the guide flange assembly (12) and is slidably connected to the inner wall of the middle cylinder of the guide flange assembly (12). A sealing cover (24) is installed on the top support column of the guide flange assembly (12). The sealing cover (24) is threadedly connected to the top support column of the guide flange assembly (12). The guide seal (25) is located at the bottom of the sealing cover (24).

7. The single spring reset safety valve of claim 1, wherein, The cam groove (15) is triangular in shape and is composed of a straight groove (32), a flat groove (31) and an inclined groove (33). The inclined groove (33) is connected to the middle of the straight groove (32). The flat groove (31) and the straight groove (32) are shallow grooves with the same depth. The top of the inclined groove (33) is a deep groove, and the bottom is a smooth transition structure from the deep groove to the shallow groove. The depth of the deep groove is greater than the depth of the shallow groove.

8. The single spring reset safety valve of claim 1, wherein, The positioning guide device (3) also includes a telescopic spring (19), a screw A (20) and a pressure cap (21). A limit plate is provided in the middle of the positioning guide pin (18). The telescopic spring (19) is sleeved on the end of the positioning guide pin (18) away from the hollow piston rod (2). The pressure cap (21) is fixed to the side wall of the valve body (1) by the screw A (20).

9. The single spring reset safety valve of claim 1, wherein, The valve body (1) is equipped with a protective cover (9) on the top, and the protective cover (9) is threadedly connected to the outer wall of the valve body (1).

10. An assembly method for a single-spring return safety valve capable of achieving a large opening degree, characterized in that, Includes the following steps: Step 1: Install the anti-rotation pad (11) on the step surface A (36) inside the valve body (1), so that the end of the outer anti-rotation tooth A (30) of the anti-rotation pad (11) is located in the anti-rotation groove (22). Then install the compression spring (4) on the upper part of the anti-rotation pad (11), with the bottom of the compression spring (4) fitted on the positioning step (39). Install the anti-rotation pressure plate (10) on the top of the compression spring (4), so that the top of the compression spring (4) is fitted on the outside of the positioning boss (40), and the end of the outer anti-rotation tooth B (38) of the anti-rotation pressure plate (10) is located in the anti-rotation groove (22). Step 2: Install the pointer (6) in the pointer socket (27) of the anti-rotation pressure plate (10) through the observation window on the side wall of the valve body (1), and at the same time install the pressure scale (5) in the observation window. Step 3: Install adjusting nut (7) on top of anti-rotation pressure plate (10), and press adjusting nut (7) against the upper surface of anti-rotation pressure plate (10); Step 4: Install the hollow piston rod (2) through the bottom opening of the valve body (1). First, insert the top cylinder of the hollow piston rod (2) into the inner hole of the anti-rotation pad (11), compression spring (4), anti-rotation pressure plate (10) and adjusting nut (7). Then, install the positioning guide device (3) in the mounting hole on the side wall of the valve body (1). At the same time, rotate the hollow piston rod (2) to insert the end of the positioning guide pin (18) into the top of the inclined groove of the cam groove (15). Step 5: Install the guide seal (25) and the sealing gland (24) on the top of the top support column of the guide flange assembly (12), install the piston seal ring (13) in the inner hole of the lower part of the valve body (1), so that the top surface of the piston seal ring (13) is close to the bottom surface of the step surface B (37), and then install the guide flange assembly (12) in the inner hole of the lower part of the valve body (1), so that the top surface of the middle cylinder of the guide flange assembly (12) presses the bottom surface of the piston seal ring (13). At the same time, the guide seal (25) and the sealing gland (24) are both located in the bottom inner hole of the hollow piston rod (2). Finally, fix the guide flange assembly (12) to the bottom of the valve body (1) with screw B (26).

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