A mechanical seal for a high-pressure safety injection pump

Abstract

The present invention discloses a mechanical seal for a high-pressure safety injection pump, which includes a compensation ring assembly, a non-compensation ring assembly, a spring seat assembly, a mandrel, a shaft sleeve, a snap ring, an anti-rotation pin, and a locking assembly. The dynamic seal of the medium is achieved by the contact between the end faces of the compensation ring and the non-compensation ring of the compensation ring assembly and the non-compensation ring assembly. The present invention can enable the mechanical seal part of the high-pressure safety injection pump to have good sealing performance, be quite stable and reliable during operation, and greatly improve the safety of the equipment.

Description

Technical Field

[0001] The present invention relates to a mechanical seal in the field of nuclear power equipment, specifically to a mechanical seal for a high-pressure safety injection pump. Background Art

[0002] . The high-pressure safety injection pump is an important device in the primary loop safety injection system of a nuclear power plant. Its function is that when a medium or small break loss-of-coolant accident occurs in the primary loop system of the nuclear reactor, the pump starts immediately to inject water into the reactor to prevent the accident from further expanding and ensure the safety of the nuclear power plant.

[0003] The high-pressure safety injection pump has important significance and functions in the primary loop of a nuclear power plant. Once the high-pressure safety injection pump fails and shuts down, it will bring unpredictable serious consequences. Therefore, the safety and reliability during the operation of the high-pressure safety injection pump become crucial. The mechanical seal of the high-pressure safety injection pump mainly plays a sealing role to prevent the leakage of the medium during the operation of the pump. The medium in the pump is radioactive boron-containing water with a temperature of 70 - 95°C. Therefore, the sealing performance of the mechanical seal is particularly important. In the prior art, the assembly process of the mechanical seal of the high-pressure safety injection pump is complex in structure, the processing difficulty of parts is high, and it is not easy to replace spare parts. In the existing product structure, the small spring rotates together with the shaft sleeve and will be affected by multiple forces such as centrifugal force and medium scouring force during rotation. Considering the actual working conditions, it is not very conducive to the operation of the mechanical seal. During use, the compensation ring seat needs to float frequently to ensure the normal operation of the friction pair end face. Therefore, the compensation ring seat and the spring seat will be damaged due to long-term contact friction with the O-ring, resulting in possible failure of the seal here. In addition, in the locking device used to fix the shaft sleeve and the core shaft, the existing structures basically use set screws for fastening, but over time, it will damage the surface of the shaft and there is a potential risk of slipping. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned technical defects and provide a mechanical seal for a high-pressure safety injection pump.

[0005] To solve the above technical problem, the technical solution provided by the present invention is a mechanical seal for a high-pressure safety injection pump: including a compensation ring assembly, a non-compensation ring assembly, a spring seat assembly, a core shaft, a shaft sleeve, a snap ring, an anti-rotation pin, and a locking assembly. The compensation ring assembly and the non-compensation ring assembly achieve dynamic sealing of the medium through the contact of the end faces of the compensation ring and the non-compensation ring.

[0006] Further, the non-compensating ring assembly includes a non-compensating ring and a non-compensating ring O-ring. The bushing is of a cylindrical structure. Threads and an annular groove structure are machined on the outer side of one end of the bushing, and a stepped groove is machined at the other end. The non-compensating ring is installed in the groove, and a sealing ring groove is machined at the bottom of the groove for installing the non-compensating ring O-ring. A snap ring groove is machined on the inner side of the groove at the step of the bushing, a spiral groove is machined on the outer side of the groove and a plurality of through holes are machined. A step is machined on the inner side of the bushing body away from the threads. When the step cooperates with the mandrel, a bushing O-ring is installed to achieve a static sealing function. The anti-rotation pin is a cylinder, the large end face is spherical. When installed, the small end is inserted into the through hole of the bushing, and the large end is on the inner side of the bushing. The non-compensating ring is of an annular structure, and a semi-circular notch is machined on its side for cooperating with the anti-rotation pin to achieve circumferential fixation. The snap ring is installed in the snap ring groove to achieve axial fixation of the non-compensating ring. A cylindrical pin is provided at one end of the bushing, and the bushing is axially fixed to the mandrel through the cylindrical pin.

[0007] Further, the compensating ring assembly includes a compensating ring, a compensating ring seat and a compensating ring O-ring. The compensating ring seat is of a cylindrical structure. A plurality of steps are machined on the compensating ring seat. A groove is machined at the large-diameter end of the compensating ring seat for installing the compensating ring and the compensating ring O-ring respectively. A plurality of blind holes and a plurality of threaded holes are provided on the end face of the small-diameter end of the compensating ring seat. Springs are installed in the blind holes, and guide pins are provided in the threaded holes. A snap ring groove and a plurality of through holes are machined on the inner side of the groove at the large diameter of the compensating ring seat. The structure of the compensating ring is similar to that of the non-compensating ring. The compensating ring cooperates with the anti-rotation pin to maintain circumferential fixation. The anti-rotation pin is a cylinder, the large end face of the anti-rotation pin is spherical. When installed, the small end of the anti-rotation pin is inserted into the through hole of the bushing, and the large end is on the inner side of the bushing. The snap ring is installed in the snap ring groove to achieve axial fixation of the non-compensating ring.

[0008] Further, the spring seat assembly includes a spring seat, a plurality of springs, a spring seat O-ring, guide pins, bolt B and a positioning block. The spring seat is of an annular structure. A plurality of through holes corresponding to the threaded holes on the compensating ring seat are machined on the end face of the spring seat for the guide pins to pass through. The guide pins are round-headed threaded pins, and the guide pins are fixed in the threaded holes of the compensating ring seat through the holes of the spring seat, so that the compensating ring seat and the spring seat are circumferentially fixed and axially movable. A spring seat O-ring is installed between the spring seat and the compensating ring seat. One end of the spring abuts against the bottom of the blind hole of the compensating ring seat, and the other end abuts against the spring seat, thereby providing elastic force for the friction pair end face. The structure of multiple springs makes the pressure on the friction pair end face uniform and more stable, ensuring a good operating state. The positioning block is installed on the spring seat and fixed through the bolt B. The end of the positioning block away from the bolt B is embedded in the annular groove of the bushing, thereby realizing the function of a modular assembly, making the assembly process simpler and avoiding possible additional impacts during the assembly process.

[0009] Further, the locking assembly includes a locking ring A, a locking ring B, a bolt A, and a locking washer. The locking ring B is of a ring structure. A plurality of threaded holes corresponding to the locking ring A are machined on the end face of the locking ring B. Threads are machined on the inner ring of the locking ring B and are matched with the threads of the shaft sleeve. A plurality of notches are machined on the outer ring of the locking ring B for tightening with a special tool. The structure of the locking ring A is similar to that of the locking ring B. Through holes corresponding to the threaded holes of the locking ring B are machined on the end face of the locking ring A. The locking ring B is threadedly connected to the shaft sleeve, the locking ring A is threadedly connected to the core shaft, and the locking ring B and the locking ring A are tightly connected by the bolt A. Meanwhile, the bolt can be prevented from loosening under the action of the locking washer. Due to this special connection method, the core shaft and the shaft sleeve can be kept fixed.

[0010] The present invention can make the mechanical seal part of the high-pressure safety injection pump have good sealing performance during operation, be quite stable and reliable, and greatly improve the safety of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic structural diagram of a mechanical seal for a high-pressure safety injection pump according to the present invention Figure 1 .

[0012] Figure 2 is a schematic structural diagram of a mechanical seal for a high-pressure safety injection pump according to the present invention Figure 2 .

[0013] Figure 3 is a schematic diagram of the shaft sleeve structure of a mechanical seal for a high-pressure safety injection pump according to the present invention.

[0014] As shown in the figure: 1. Shaft sleeve, 2. Non-compensating ring, 3. Anti-rotation pin, 4. Spring seat O-ring, 5. Compensating ring, 6. Compensating ring seat, 7. Spring seat, 8. Spring, 9. Locking ring B, 10. Bolt A, 11. Locking ring A, 12. Cylindrical pin, 13. Guide pin, 14. Compensating ring seat O-ring, 15. Compensating ring O-ring, 16. Non-compensating ring O-ring, 17. Shaft sleeve O-ring, 18. Snap ring, 19. Core shaft, 20. Locking washer, 21. Positioning block, 22. Bolt B. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] The following further elaborates on a mechanical seal for a high-pressure safety injection pump according to the present invention with reference to the accompanying drawings.

[0016] Combined with the attached Figures 1-3, A mechanical seal for a high-pressure safety injection pump, comprising a compensation ring assembly, a non-compensation ring assembly, a spring seat assembly, a mandrel 19, a shaft sleeve 1, a snap ring 18, an anti-rotation pin 3, and a locking assembly. The dynamic seal of the medium is achieved by the end faces of the compensation ring 5 and the non-compensation ring 2 in contact with each other between the compensation ring assembly and the non-compensation ring assembly.

[0017] The non-compensation ring assembly includes a non-compensation ring 2 and a non-compensation ring O-ring 16. The shaft sleeve 1 is of a cylindrical structure. One end of the shaft sleeve 1 is machined with a thread and an annular groove structure on the outer side, and the other end is machined with a stepped groove. The non-compensation ring 2 is installed in the groove, and a sealing ring groove is machined at the bottom of the groove for installing the non-compensation ring O-ring 16. A snap ring groove is machined on the inner side of the groove at the step of the shaft sleeve 1, a spiral groove and multiple through holes are machined on the outer side of the groove. A step is machined on the inner side of the shaft sleeve 1 away from the thread end. When the step cooperates with the mandrel 19, a shaft sleeve O-ring 17 is installed to achieve the static seal function. The anti-rotation pin 3 is a cylinder, and the large end face is spherical. When installed, the small end is inserted into the through hole of the shaft sleeve 1, and the large end is on the inner side of the shaft sleeve 1. The non-compensation ring 2 is of a ring structure, and a semi-circular notch is machined on its side for cooperating with the anti-rotation pin 3 to achieve circumferential fixation. The snap ring 18 is installed in the snap ring groove to achieve the axial fixation of the non-compensation ring 2. A cylindrical pin 12 is provided at one end of the shaft sleeve 1, and the shaft sleeve 1 is axially fixed to the mandrel 19 through the cylindrical pin 12.

[0018] The compensation ring assembly includes a compensation ring 5, a compensation ring seat 6, and a compensation ring O-ring 15. The compensation ring seat 6 is of a cylindrical structure. Multiple steps are machined on the compensation ring seat 6. A groove is machined at the large-diameter end of the compensation ring seat 6 for installing the compensation ring 5 and the compensation ring O-ring 15 respectively. The end face of the small-diameter end of the compensation ring seat 6 is provided with several blind holes and multiple threaded holes. A spring 8 is installed in the blind hole, and a guide pin 13 is provided in the threaded hole. A snap ring groove and multiple through holes are machined on the inner side of the groove at the large diameter of the compensation ring seat 6. The structure of the compensation ring 5 is similar to that of the non-compensation ring 2. The compensation ring 5 cooperates with the anti-rotation pin 3 to maintain circumferential fixation. The anti-rotation pin 3 is a cylinder, and the large end face of the anti-rotation pin 3 is spherical. When installed, the small end of the anti-rotation pin 3 is inserted into the through hole of the shaft sleeve 1, and the large end is on the inner side of the shaft sleeve 1. The snap ring 18 is installed in the snap ring groove to achieve the axial fixation of the non-compensation ring 2.

[0019] The spring seat assembly includes a spring seat 7, multiple springs 8, a spring seat O-ring 4, a guide pin 13, a bolt B22, and a positioning block 21. The spring seat 7 is of an annular structure. Multiple through holes corresponding to the threaded holes on the compensating ring seat 6 are machined on the end face of the spring seat 7 for the guide pin 13 to pass through. The guide pin 13 is a round-headed threaded pin. The guide pin 13 is fixed in the threaded hole of the compensating ring seat 6 through the hole of the spring seat 7, so that the compensating ring seat 6 and the spring seat 7 are circumferentially fixed and axially movable. A compensating ring seat O-ring 14 is installed between the spring seat 7 and the compensating ring seat 6. One end of the spring 8 abuts against the bottom of the blind hole of the compensating ring seat 6, and the other end abuts against the spring seat 7, thereby providing elastic force for the friction pair end face. The structure of multiple springs makes the pressure on the friction pair end face uniform and more stable, ensuring a good operating state. The positioning block 21 is installed on the spring seat 7 and fixed by the bolt B22. The end of the positioning block 21 away from the bolt B22 is embedded in the annular groove of the shaft sleeve 1, thereby realizing the function of a modular assembly, making the assembly process simpler and avoiding possible additional impacts during the assembly process.

[0020] The locking assembly includes a locking ring A11, a locking ring B9, a bolt A10, and a lock washer 20. The locking ring B9 is of an annular structure. Multiple threaded holes corresponding to the locking ring A11 are machined on the end face of the locking ring B9. The inner ring of the locking ring B9 is threaded and matched with the thread of the shaft sleeve 1. Multiple notches are machined on the outer ring of the locking ring B9 for tightening with a special tool. The structure of the locking ring A11 is similar to that of the locking ring B9. Through holes corresponding to the threaded holes of the locking ring B9 are machined on the end face of the locking ring A11. The locking ring B9 is threadedly connected to the shaft sleeve 1, and the locking ring A11 is threadedly connected to the mandrel 19. The locking ring B9 and the locking ring A11 are connected and fastened by the bolt A10. At the same time, the bolt can be prevented from loosening under the action of the lock washer 20. Due to this special connection method, the mandrel 19 and the shaft sleeve 1 can be kept fixed.

[0021] The present invention works as follows: Before working, the compensating ring assembly and the spring seat assembly can be connected and assembled through the guide pin 13. At this time, the spring 8 can be partially pre-compressed. Then, the non-compensating ring assembly and the spring seat assembly are assembled and fixed through the positioning block 21. At this time, the friction pair end faces are in contact, and the spring 8 is in a pre-compressed state, avoiding damage to the friction pair during the subsequent assembly process. At the same time, the installation process can be simplified to make it simple and safe. When the whole is assembled on the high-pressure safety injection pump, the positioning block 21 is removed, and this is the working state at this time. During work, the shaft sleeve O-ring 17, the compensating ring O-ring 15, the non-compensating ring O-ring 16, the spring seat O-ring 4, and the compensating ring seat O-ring 14 are all circumferentially fixed, achieving the effect of static sealing. The non-compensating ring 2 and the mandrel 19 rotate simultaneously, and the compensating ring 5 is circumferentially fixed. The two rings achieve the sealing effect by contacting each other through the end faces.

[0022] Beneficial effects of the present invention:

[0023] 1. The mechanical seal of the high-pressure injection pump is designed as a cartridge type, which has the advantages of being convenient and quick in installation, accurate in assembly position, and avoiding bumping into the friction pair surface during assembly;

[0024] 2. The high-pressure injection pump's mechanical seal is designed with a spring-stationary design and a multi-spring structure. Because high-pressure injection pump mechanical seals operate at high rotational speeds, this spring-stationary design protects the spring from centrifugal forces and reduces the impact of scouring during rotation. The multi-spring structure also ensures uniform force distribution on the friction pair's end faces, preventing poor end face condition caused by uneven spring force.

[0025] 3. The mechanical seal sleeve of the high-pressure injection pump is designed with a special spiral structure. During the rotation process, the special spiral structure on the surface can produce a pumping effect, forcing the internal medium to circulate, thereby achieving continuous circulation and cooling of the medium, so that the end faces of the friction pair are in good operating condition.

[0026] 4. The designated positions of the non-compensating ring seat and spring seat of the mechanical seal of the high-pressure injection pump are sprayed with a hard alloy coating. After spraying, the wear resistance of the area is greatly improved, solving the problem of seal failure caused by wear of the O-ring.

[0027] 5. The unique locking design of the mechanical seal of the high-pressure injection pump can achieve greater torque transmission without damaging the sleeve surface, reducing the risk of slipping.

[0028] 6. The guide pin of the mechanical seal of the high-pressure injection pump adopts the form of a threaded pin with a step, which is simple and convenient to install. It can play the role of pre-compressing the spring during the installation process, and also play the role of circumferentially fixing the non-compensating ring seat.

[0029] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A mechanical seal for a high-pressure safety injection pump, comprising a compensation ring assembly, a non-compensation ring assembly, a spring seat assembly, a mandrel (19), a shaft sleeve (1), a snap ring (18), an anti-rotation pin (3), and a locking assembly, characterized in that: The compensation ring assembly and the non-compensation ring assembly achieve dynamic sealing of the medium through the end faces of the compensation ring (5) and the non-compensation ring (2) being in contact with each other; The non-compensation ring assembly includes a non-compensation ring (2) and a non-compensation ring O-ring (16). The bushing (1) has a cylindrical structure. Threads and an annular groove structure are machined on the outer side of one end of the bushing (1), and a stepped portion with a groove is machined at the other end. The non-compensation ring (2) is installed in the groove, and a sealing ring groove is machined at the bottom of the groove for installing the non-compensation ring O-ring (16). A snap ring groove is machined on the inner side of the groove at the stepped portion of the bushing (1), a spiral groove is machined on the outer side of the groove and multiple through holes are machined. A stepped portion is machined on the inner side of the cylindrical body of the bushing (1) away from the threads. When the stepped portion cooperates with the mandrel (19), a bushing O-ring (17) is installed to achieve the function of static sealing. The anti-rotation pin (3) is a cylinder, and the end face of the large end is spherical. During installation, the small end is inserted into the through hole of the bushing (1), and the large end is on the inner side of the bushing (1). The non-compensation ring (2) has an annular structure, and a semi-circular notch is machined on its side surface for cooperating with the anti-rotation pin (3) to achieve circumferential fixation. The snap ring (18) is installed in the snap ring groove to achieve axial fixation of the non-compensation ring (2). A cylindrical pin (12) is provided at one end of the bushing (1), and the bushing (1) achieves axial fixation with the mandrel (19) through the cylindrical pin (12); The compensation ring assembly includes a compensation ring (5), a compensation ring seat (6), and a compensation ring O-ring (15). The compensation ring seat (6) has a cylindrical structure. Multiple stepped portions are machined on the compensation ring seat (6). A groove is machined at the large-diameter end of the compensation ring seat (6) for installing the compensation ring (5) and the compensation ring O-ring (15) respectively. A number of blind holes and multiple threaded holes are provided on the end face of the small-diameter end of the compensation ring seat (6). A spring (8) is installed in the blind hole, and a guide pin (13) is provided in the threaded hole. A snap ring groove and multiple through holes are machined on the inner side of the groove at the large diameter of the compensation ring seat (6). The compensation ring (5) cooperates with the anti-rotation pin (3) to maintain circumferential fixation. The anti-rotation pin (3) is a cylinder, and the end face of the large end of the anti-rotation pin (3) is spherical. During installation, the small end of the anti-rotation pin (3) is inserted into the through hole of the bushing (1), and the large end is on the inner side of the bushing (1). The snap ring (18) is installed in the snap ring groove to achieve axial fixation of the non-compensation ring (2); The spring seat assembly includes a spring seat (7), a plurality of springs (8), a spring seat O-ring (4), a guide pin (13), a bolt B (22), and a positioning block (21). The spring seat (7) is of an annular structure. A plurality of through holes corresponding to the threaded holes on the compensation ring seat (6) are machined on the end face of the spring seat (7) for the guide pin (13) to pass through. The guide pin (13) is a round-headed threaded pin. The guide pin (13) is fixed in the threaded hole of the compensation ring seat (6) through the hole of the spring seat (7), so that the compensation ring seat (6) and the spring seat (7) are circumferentially fixed and axially movable. A compensation ring seat O-ring (14) is installed between the spring seat (7) and the compensation ring seat (6). One end of the spring (8) abuts against the bottom of the blind hole of the compensation ring seat (6), and the other end abuts against the spring seat (7). The positioning block (21) is installed on the spring seat (7) and fixed by the bolt B (22). The end of the positioning block (21) away from the bolt B (22) is embedded in the annular groove of the bushing (1). The locking assembly includes a locking ring A (11), a locking ring B (9), a bolt A (10), and a lock washer (20). The locking ring B (9) is of an annular structure. A plurality of threaded holes corresponding to the locking ring A (11) are machined on the end face of the locking ring B (9). The inner circle of the locking ring B (9) is threaded and matches the thread of the bushing (1). A plurality of notches are machined on the outer circle of the locking ring B (9) for tightening with a special tool. Through holes corresponding to the threaded holes of the locking ring B (9) are machined on the end face of the locking ring A (11). The locking ring B (9) is threadedly connected to the bushing (1), the locking ring A (11) is threadedly connected to the mandrel (19), and the locking ring B (9) and the locking ring A (11) are connected and fastened by the bolt A (10).

Images