An active stop seal device for a nuclear main pump

Abstract

The present invention relates to an active parking seal device for a nuclear main pump, comprising: a dynamic seal assembly for being fixed on a rotating shaft or a shaft sleeve and rotating therewith; a static seal ring axially slidably arranged on a seal housing along the rotating shaft or the shaft sleeve, a sealed cavity being formed between the static seal ring and the seal housing, and a gas injection pipeline being communicated with the sealed cavity; an elastic member located between the seal housing and the static seal ring, such that the static seal ring always has a tendency to move away from the dynamic seal assembly; a guiding member located between the static seal ring and a third seal housing, for providing guidance during the sliding of the static seal ring, and through which the situation of jamming between the static seal ring and the seal housing can be effectively reduced or eliminated, so that the parking seal is more reliable during use and no medium leakage occurs.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power, and more particularly to an active stop seal device for a nuclear main pump. Background Art

[0002] Nuclear power is a safe, clean and efficient energy source. Developing nuclear power is of great strategic significance for China to meet power demand, optimize energy structure, ensure energy security and promote sustainable economic development; developing nuclear power is an effective way to reduce environmental pollution and prevent the greenhouse effect; developing nuclear power is an important measure to maintain the integrity of the nuclear industry system and promote the upgrading of China's equipment manufacturing industry.

[0003] In a nuclear power plant, the main pump static shaft seal is an important component of the main pump and is part of the primary circuit pressure boundary. The main pump static shaft seal consists of a first seal, a second seal, a third seal and an active stop seal arranged in series. The active stop seal prevents reactor coolant from leaking along the pump shaft into the reactor building under the conditions that the main pump loses both RCV injection water and RRI cooling water simultaneously, and the first seal, the second seal and the third seal fail simultaneously.

[0004] However, the currently adopted stop seal structure is unreliable in use, and there may be a situation of medium leakage to the outside. Summary of the Invention

[0005] In order to solve the problem of the unreliability of the existing stop seal structure, the present application provides an active stop seal device for a nuclear main pump.

[0006] The above object of the present invention is achieved by the following technical solutions: An active stop seal device for a nuclear main pump, comprising:

[0007] A seal housing for sleeving outside a rotating shaft or a shaft sleeve, and the rotating shaft or the shaft sleeve can rotate relative to the seal housing;

[0008] A dynamic seal assembly for being fixed on the rotating shaft or the shaft sleeve and rotating with the rotating shaft or the shaft sleeve;

[0009] A static seal ring is axially slidably arranged on the seal housing along the rotating shaft or the shaft sleeve. The static seal ring is located between the dynamic seal assembly and the third seal. A sealed cavity is formed between the static seal ring and the seal housing. A gas injection pipeline is communicated with the sealed cavity. The static seal ring slides in response to the opening of the gas injection pipeline and cooperates with the dynamic seal assembly to form a sealing surface;

[0010] An elastic member is located between the seal housing and the static seal ring, so that the static seal ring always has a tendency to move away from the dynamic seal assembly side;

[0011] The guiding member is located between the static sealing ring member and the third sealing housing and is used to provide guidance during the sliding of the static sealing ring member.

[0012] By adopting the above technical solution, when the main pump is operating normally, the elastic member provides an elastic force to separate the static sealing ring member from the dynamic sealing assembly, preventing frictional damage caused by the mis-start of the static sealing ring member; when the main pump fails and stops, compressed gas is injected through the gas injection pipeline, and the static sealing ring member is pushed by the compressed gas to overcome the elastic force and slide to fit with the dynamic sealing assembly, forming a sealing surface. Through the sealing surface, the leakage of the reactor coolant can be restricted. During use, since the force on the static sealing ring member is relatively complex, the static sealing ring member may get stuck during the sliding fit with the sealing housing, resulting in the failure of the stop seal. Currently, preventing such a stuck situation requires higher machining accuracy, and the sizes of the sealing housing and the static sealing ring member are both large, so the machining difficulty is very high. By providing the guiding member, the static sealing ring member is not likely to get stuck during use. At the same time, the guiding member has a small size and low machining difficulty, making it easier for mass production; through the guiding member, the situation of the static sealing ring member getting stuck between the sealing housing can be effectively reduced or eliminated, making the stop seal more reliable during use and preventing the leakage of the medium.

[0013] Preferably, the dynamic sealing assembly includes:

[0014] The dynamic sealing ring is slidably sleeved on the rotating shaft or the shaft sleeve and is used to cooperate with the static sealing ring member to form a sealing surface;

[0015] The locking ring surrounds the dynamic sealing ring and is detachably fixed on the rotating shaft or the shaft sleeve and is used to lock and fix the dynamic sealing ring on the rotating shaft or the shaft sleeve.

[0016] By adopting the above technical solution, the locking ring can fix the dynamic sealing ring circumferentially along the dynamic sealing ring, which is more reliable than directly fixing with bolts and has higher connection strength.

[0017] Preferably, a flange is provided on the rotating shaft or the shaft sleeve, the locking ring has a locking surface that fits with the dynamic sealing ring along the axial direction of the rotating shaft or the shaft sleeve, and the locking ring is detachably connected to the flange along the axial direction of the rotating shaft or the shaft sleeve;

[0018] The dynamic sealing assembly further includes: a limiting ring, which is sleeved on the rotating shaft or the shaft sleeve and is located between the dynamic sealing ring and the flange, and is fixed on the rotating shaft or the shaft sleeve by the locking ring, and an adjustment gap is provided between the locking ring and the flange.

[0019] By adopting the above technical solution, due to certain errors in processing and assembly, the distance between the dynamic sealing ring and the static sealing ring after assembly does not meet the design requirements. However, through the limiting ring, the distance between the dynamic sealing ring and the static sealing ring can be adjusted to ensure that the design requirements can be met after assembly. When adjusting, different thickness limiting rings can be replaced to change the axial position of the dynamic sealing ring on the rotating shaft or the shaft sleeve, and the adjustment is simple and convenient;

[0020] During assembly, the flange will be connected to the pump shaft by bolts. By setting the locking ring, the bolts connecting the pump shaft can be abutted, preventing the bolts connecting the pump shaft from loosening or detaching during operation, making the equipment work more stably.

[0021] Preferably, the limiting ring includes at least two split limiting units, and each split limiting unit has the same radian.

[0022] By adopting the above technical solution, since the position relationship between the dynamic sealing ring and the static sealing ring needs to be accurately measured after the entire parking seal is assembled, by setting the limiting ring as a split ring, the limiting ring can be quickly replaced without disassembling other sealing components, facilitating the adjustment of the position of the dynamic sealing ring after assembly; during adjustment, loosen the locking ring and pull out the limiting ring along the axial direction perpendicular to the shaft sleeve or the rotating shaft.

[0023] Preferably, the locking ring includes at least two split locking units, and each split locking unit has the same radian.

[0024] By adopting the above technical solution, due to the cooperation relationship between the locking ring and the limiting ring, when replacing the limiting ring, it is not easy for the locking ring to slide axially along the shaft sleeve or the rotating shaft, and thus it is not easy to replace the limiting ring. By setting the locking ring as a split ring, the locking ring can be directly disassembled along the axial direction perpendicular to the rotating shaft or the shaft sleeve, facilitating the subsequent disassembly and replacement of the limiting ring.

[0025] Preferably, a sealing ring is provided at the sealing surface.

[0026] By adopting the above technical solution, through the sealing ring, a sealing boundary can be formed at the sealing surface to avoid the occurrence of medium leakage after the main pump stops abnormally; since the contact between the dynamic sealing ring and the static sealing ring is an annular surface, there are very high processing accuracy requirements for the surfaces where the dynamic sealing ring and the static sealing ring are in contact with each other, and at the same time, there are also very high assembly accuracy requirements for the two. Therefore, after the dynamic sealing ring and the static sealing ring are mutually attached, there may be a situation where the attachment is not tight, and it is easy to cause medium leakage. However, through the sealing ring, when the static sealing ring is in close contact with the dynamic sealing ring, the gap between the dynamic sealing ring and the static sealing ring can be completely filled, preventing the medium from leaking through the gap between the static sealing ring and the dynamic sealing ring.

[0027] Preferably, the elastic member includes:

[0028] A first helical spring, one end of which abuts against the sealing housing and the other end abuts against the static seal ring, so that the static seal ring always has a tendency to move away from the dynamic seal ring side;

[0029] A second helical spring, located inside the inner ring of the first helical spring, wherein the central axis of the second helical spring is parallel to the central axis direction of the first helical spring.

[0030] By adopting the above technical solution, through the first helical spring and the second helical spring, it is possible to prevent the static seal ring from being mis-started and contacting and rubbing against the dynamic seal ring during the normal operation of the main pump, thereby causing damage.

[0031] Preferably, the free length of the second helical spring is less than the free length of the first helical spring; when the static seal ring is located on the side away from the dynamic seal ring, the second helical spring is in the free length state.

[0032] By adopting the above technical solution, when driving the static seal ring, only the first helical spring exerts an elastic force on the static seal ring. At this time, it is convenient for the static seal ring to start sliding. As the static seal ring slides, the second helical spring will exert an elastic force on the static seal ring, increasing the power required for the static seal ring to continue sliding. Therefore, it is possible to avoid the mis-start of the static seal ring, and while facilitating the start of the static seal ring, it is possible to avoid the situation where the static seal ring contacts and rubs against the dynamic seal ring and is damaged when the static seal ring is mis-started.

[0033] Preferably, a spring guide post is provided between the static seal ring and the sealing housing. The axial direction of the spring guide post is parallel to the axial direction of the rotating shaft or the shaft sleeve. One end of the spring guide post is fixed to the static seal ring, and the other end is slidably connected to the sealing housing. The second helical spring is sleeved on the spring guide post and has a clearance fit with the spring guide post. A limiting groove for cooperating with the outer ring of the first helical spring is provided on the sealing housing and / or the static seal ring, and the first helical spring has a clearance fit with the limiting groove.

[0034] By adopting the above technical solution, the spring guide post can prevent the first helical spring and the second helical spring from becoming unstable during operation, avoiding the situation where the static seal ring is stuck and the parking seal fails. Through the limiting groove, the first helical spring and the second helical spring can be kept coaxial, avoiding the situation where the first helical spring and the second helical spring are intertwined during operation.

[0035] Preferably, the static seal ring is slidably fitted between the third sealing side and the third sealing housing. An anti-extrusion sealing ring is provided at the sliding fit between the static seal ring and the third sealing housing. The anti-extrusion sealing ring includes a rubber ring and a metal ring located inside the rubber ring.

[0036] By adopting the above technical solution, there is a relatively large gap between the static seal ring and the third seal housing. Under specific working conditions, there will be a relatively large pressure here, so it is easy to extrude the sealing ring here, resulting in seal failure. Therefore, an anti-extrusion sealing ring is selected, which can ensure normal sealing and avoid the situation of the seal being extruded.

[0037] In summary, the present invention includes at least one of the following beneficial technical effects:

[0038] 1. A sealing surface is formed between the static seal ring and the dynamic seal assembly, which can limit the leakage of reactor coolant. Through the guide member, the jamming between the static seal ring and the seal housing can be effectively reduced or eliminated, making the parking seal more reliable in use and not easily or not leaking the medium outward;

[0039] 2. The first helical spring and the second helical spring can make the static seal ring easier to start while avoiding the mis-start of the static seal ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a schematic structural diagram of Embodiment 1.

[0041] Figure 2 is a schematic structural diagram of the anti-extrusion sealing ring.

[0042] Figure 3 is a partial structural diagram of Embodiment 1.

[0043] Figure 4 is a schematic structural diagram of the limiting ring.

[0044] Figure 5 is a schematic structural diagram of the locking ring.

[0045] Figure 6 is a partial structural diagram of Embodiment 2.

[0046] In the figure, 1, rotating shaft; 2, shaft sleeve; 3, seal housing; 4, dynamic seal assembly; 41, dynamic seal ring; 42, locking ring; 421, locking surface; 422, locking unit; 43, limiting ring; 431, limiting unit; 5, static seal ring; 6, elastic member; 61, first helical spring; 62, second helical spring; 7, guide member; 8, sealing surface; 9, flange; 10, adjusting gap; 11, sealing ring; 12, spring guide post; 13, limiting groove; 14, third seal; 15, third seal housing; 16, anti-extrusion sealing ring; 161, rubber ring; 162, metal ring; 17, sealed cavity; 18, gas injection pipeline; 19, sealing groove; 20, connecting bolt; 21, groove; 22, sliding hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The present invention will be further described in detail below with reference to the accompanying drawings.

[0048] Embodiment 1:

[0049] Referring to Figure 1 and 3 , an active parking seal device for a nuclear main pump disclosed by the present invention includes a seal housing 3 connected to the end of a third seal housing 15 and a dynamic seal assembly 4 connected to a rotating shaft 1 or a shaft sleeve 2. The seal housing 3 is sleeved outside the rotating shaft 1 or the shaft sleeve 2, and there is a clearance fit between the seal housing 3 and the rotating shaft 1 or the shaft sleeve 2, so that the shaft sleeve 2 or the rotating shaft 1 can rotate relative to the seal housing 3. A static seal ring member 5 is arranged in the seal housing 3, and the static seal ring member 5 is slidably arranged along the axial direction of the rotating shaft 1 or the shaft sleeve 2. When the static seal ring member 5 slides to the uppermost end, the static seal ring member 5 can cooperate with the dynamic seal assembly 4 to form a sealing surface 8, and the sealing surface 8 can prevent the leakage of the medium in case of emergencies; the static seal ring member 5 is slidably matched between the third seal 14 side and the third seal housing 15, and an anti-extrusion sealing ring 16 is arranged at the sliding fit position between the static seal ring member 5 and the third seal housing 15. In this embodiment, a sealing groove 19 is formed in the static seal ring member 5, and the anti-extrusion sealing ring 16 is located in the sealing groove 19.

[0050] Among them, as Figure 2 shown, the anti-extrusion sealing ring 16 includes a rubber ring 161 and a metal ring 162 located inside the rubber ring 161, and the two are solidified together. The metal ring 162 can effectively prevent the anti-extrusion sealing ring 16 from coming out of the sealing groove 19. In this embodiment, there are two metal rings 162 in the anti-extrusion sealing ring 16. A part of the metal ring 162 is located outside the rubber ring 161 and a part is located inside the rubber ring 161. During use, the metal ring 162 located outside the rubber ring 161 can abut against the third seal housing 15 to prevent the anti-extrusion sealing ring 16 from coming out of the sealing groove 19.

[0051] Referring to Figure 1 , 3 , among which, a flange 9 is arranged on the rotating shaft 1 or the shaft sleeve 2. The dynamic seal assembly 4 includes a dynamic seal ring 41, a locking ring 42 and a limiting ring 43. The locking ring 42 is fixed on the flange 9 by bolts, and the axial direction of the bolts is parallel to the axial direction of the rotating shaft 1 or the rotating shaft. The dynamic seal ring 41 is fixed on the flange 9 through the locking ring 42. The limiting ring 43 is located between the flange 9 and the locking ring 42. A locking surface 421 is arranged on the locking ring 42, and the plane where the locking surface 421 is located is parallel to the horizontal plane. During use, the dynamic seal ring 41 is attached to the locking surface 421, and the dynamic seal ring 41 is tightened and fixed on the flange 9 through the locking surface 421; referring to Figure 4 and 5As shown, the limiting ring 43 includes at least two limiting units 431. In this embodiment, the limiting unit 431 is divided into three petals, and the radian of each petal of the limiting unit 431 is 120 degrees; the locking ring 42 includes at least two locking units 422. In this embodiment, the locking unit 422 is divided into three petals, and the radian of each petal of the locking unit 422 is 120 degrees. By setting the limiting ring 43 and the locking ring 42 as split rings, it is convenient to adjust the axial position of the dynamic seal ring 41 on the rotating shaft 1 or the shaft sleeve 2 after assembly.

[0052] Referring to Figure 3 , in order to adjust the distance of the dynamic seal ring 41 in the axial direction of the rotating shaft 1 or the shaft sleeve 2 after assembly, an adjustment gap 10 is provided between the flange 9 and the locking ring 42. Through the adjustment gap 10, the locking ring 42 has a certain displacement margin in the vertical direction, so as to facilitate adjustment when adjustment is needed later. When it is found that the distance between the dynamic seal ring 41 and the static seal ring member 5 is less than the designed distance after assembly, loosen the locking ring 42 and pull out the locking ring 42 along the axial direction perpendicular to the rotating shaft 1 or the shaft sleeve 2, then pull out the limiting ring 43 and put in a new thinner limiting ring 43, and then fix the locking ring 42 again to complete the adjustment; when it is found that the distance between the dynamic seal ring 41 and the static seal ring member 5 is greater than the designed distance after assembly, just replace the limiting ring 43 with a thicker one. The adjustment is simple and convenient and does not require disassembling other parts of the equipment.

[0053] In specific use, the flange 9 needs to be connected to the pump shaft through the connecting bolts 20, so that the pump shaft is linked with the rotating shaft 1 or the shaft sleeve 2. In actual working conditions, the connecting bolts 20 may become loose or even fall off after being used for a period of time, thus causing failures. However, the locking ring 42 can press the connecting bolts 20 against the flange 9, so that the connecting bolts 20 will not fall off during use, thus ensuring the stable operation of the equipment. A groove 21 is provided at the position of the locking ring 42 where the connecting bolts 20 are located. The head of the connecting bolts 20 is accommodated through the groove 21, which does not affect the normal use of the locking ring 42 either.

[0054] Referring to Figure 3An elastic member 6 is provided between the sealing housing 3 and the static sealing ring 5. The elastic member 6 can make the static sealing ring 5 always have a tendency to move downward along the axial direction of the rotating shaft 1 or the sleeve 2. When the equipment is working normally, the elastic member 6 can prevent the static sealing ring 5 from contacting with the dynamic sealing ring 41 and causing friction damage. The elastic member 6 includes a first coil spring 61 and a second coil spring 62. One end of the first coil spring 61 abuts against the sealing housing 3, and the other end abuts against the static sealing ring 5. The first coil spring 61 makes the static sealing ring 5 always have a tendency to move away from the dynamic sealing ring 41. The second coil spring 62 is located in the inner circle of the first coil spring 61, and the free length of the second coil spring 62 is less than the free length of the first coil spring 61. When the static sealing ring 5 is located at the lower end, the second coil spring 62 is in an uncompressed state. At this time, the static sealing ring 5 is only subjected to the elastic force of the first coil spring 61.

[0055] In order to prevent the first coil spring 61 and the second coil spring 62 from becoming unstable during operation, a spring guide column 12 is connected to the static sealing ring 5. The spring guide column 12 is cylindrical, and the axial direction of the spring guide column 12 is arranged along the vertical direction. The first coil spring 61 and the second coil spring 62 are both sleeved on the spring guide column 12; a sliding hole 22 is arranged on the sealing housing 3 opposite to one end of the spring guide column 12, and the spring guide column 12 is slidably arranged in the sliding hole 22 away from the static sealing ring 5. When the static sealing ring 5 slides along the vertical direction, the spring guide column 12 will slide in the sliding hole 22; wherein the second coil spring 62 is clearance-matched with the spring guide column 12, and a limiting groove 1 is arranged on the sealing housing 3 and / or the static sealing ring 5. 3. The first coil spring 61 is clearance-matched with the limiting groove 13. In this embodiment, the limiting groove 13 is provided on both the static sealing ring 5 and the sealing housing 3. The end of the spring guide column 12 is located at the center of the bottom wall of the limiting groove 21 on the static sealing ring 5. The limiting groove 21 on the sealing housing 3 is arranged around the sliding hole 22. The lower end of the first coil spring 61 is located in the limiting groove 13 on the static sealing ring 5, and the upper end of the first coil spring 61 is located in the limiting groove 21 on the sealing housing 3, so that the first coil spring 61 is not easy to be unstable during use and the first coil spring 61 and the second coil spring 62 are always kept concentric, so as to avoid the first coil spring 61 and the second coil spring 62 from overlapping each other during compression.

[0056] Reference Figure 1 , 3, in order to make the static seal ring 5 fit with the dynamic seal ring 41 in case of failure, a sealed cavity 17 is provided between the seal housing 3, the third seal housing 15 and the static seal ring 5. A gas injection pipeline 18 communicating with the sealed cavity 17 is opened in the seal housing 3. When compressed gas is injected into the sealed cavity 17, the static seal ring 5 will slide upward in the seal housing 3 until it fits with the dynamic seal ring 41 to form a sealing surface 8. When the gas in the sealed cavity 17 is released, the static seal ring 5 will move downward under the elastic force of the first helical spring 61 and the second helical spring 62 and return to its original position.

[0057] Among them, the static seal ring 5 will be in a position far from the dynamic seal ring 41 for a long time during use. Therefore, during use, it may be difficult to slide due to impurity precipitation, etc., resulting in an increase in the resistance when the static seal ring 5 needs to be pushed to slide. When gas is injected into the sealed cavity 17, the gas will expand in the sealed cavity 17 and push the static seal ring 5 to slide gradually. When the static seal ring 5 just starts to slide, it only receives the elastic force of the first helical spring 61 and does not receive the elastic force of the second helical spring 62. Therefore, the elastic force that the static seal ring 5 needs to overcome during initial sliding is reduced, and the elastic force is reduced in the case of increased resistance, thereby balancing the force required to start the sliding of the static seal ring 5 and avoiding the situation where it is difficult to slide when the force that the static seal ring 5 needs to overcome at the beginning of sliding is large; when the static seal ring 5 moves a certain distance, the second helical spring 62 will be compressed and gradually apply an elastic force to the static seal ring 5, so that the elastic force that needs to be overcome when the static seal ring 5 contacts the dynamic seal ring 41 is large, avoiding the situation of false contact caused by the contact between the static seal ring 5 and the dynamic seal ring 41 in the case of an earthquake or vibration.

[0058] Refer to Figure 3 , in order to avoid the situation of jamming of the static seal ring 5 during sliding, a guiding member 7 is provided between the static seal ring 5 and the third seal housing 15. In this embodiment, the guiding member 7 is a sliding column connected to the static seal ring 5. A hole matching with the sliding column is provided on the third seal housing 15. There are multiple sliding columns, which are evenly distributed along the circumference of the static seal ring 5; the sliding column can be made of friction-resistant metal, and at the same time, the sliding column is small, which is more convenient for processing, and the processing accuracy can be very high, so as to effectively prevent the static seal ring 5 from jamming during use.

[0059] Refer to Figure 3, in order to further improve the sealing effect between the static seal ring member 5 and the dynamic seal ring 41, a sealing ring 11 is provided at the sealing surface 8. The sealing ring 11 is an O-ring. In this embodiment, a clamping groove is formed on the end surface of the static seal ring member 5 facing the dynamic seal ring 41. The sealing ring 11 is embedded in the clamping groove. The cross-sectional shape of the clamping groove is a dovetail shape. The clamping groove is arranged in a circle along the circumferential direction of the static seal ring member 5. When the static seal ring member 5 and the dynamic seal ring 41 are in contact, the sealing ring 11 fills the gap between the static seal ring member 5 and the dynamic seal ring 41 at the sealing surface 8, increasing the overall sealing performance.

[0060] When an unexpected shutdown occurs, compressed gas is injected into the closed cavity 17. At this time, under the push of the compressed gas, the static seal ring member 5 will slide towards the dynamic seal ring 41 side against the elastic force, etc., until the static seal ring member 5 is in contact with the dynamic seal ring 41. At this time, the sealing ring 11 will be deformed by extrusion between the static seal ring member 5 and the dynamic seal ring 41, so that the gap between the two is completely filled, achieving a higher sealing effect.

[0061] Embodiment 2: Refer to Figure 6 , a nuclear main pump active parking seal device, which is different from Embodiment 1 in that: the sealing ring 11 is arranged on the end surface of the dynamic seal ring 41 facing the static seal ring member 5.

[0062] The embodiments of the present specific implementation manners are all preferred embodiments of the present invention, and do not limit the protection scope of the present invention accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. An active parking seal device for a nuclear main pump, characterized in that, Comprising: A sealed housing (3) for sleeving outside the rotating shaft (1) or the shaft sleeve (2), and the rotating shaft (1) or the shaft sleeve (2) can rotate relative to the sealed housing (3); A dynamic sealing assembly (4) for being fixed on the rotating shaft (1) or the shaft sleeve (2) and rotating with the rotating shaft (1) or the shaft sleeve (2); A static sealing ring member (5) axially slidingly arranged on the sealed housing (3) along the rotating shaft (1) or the shaft sleeve (2), wherein the static sealing ring member (5) is located between the dynamic sealing assembly (4) and the third seal (14), a sealed cavity (17) is formed between the static sealing ring member (5) and the sealed housing (3), a gas injection pipeline (18) is communicated with the sealed cavity (17), and the static sealing ring member (5) slides in response to the opening of the gas injection pipeline (18) and cooperates with the dynamic sealing assembly (4) to form a sealing surface (8); An elastic member (6) located between the sealed housing (3) and the static sealing ring member (5), so that the static sealing ring member (5) always has a tendency to move away from the dynamic sealing assembly (4); A guiding member (7) located between the static sealing ring member (5) and the third sealed housing (15) for providing guidance during the sliding of the static sealing ring member (5).

2. The active parking seal device for a nuclear main pump according to claim 1, characterized in that, The dynamic sealing assembly (4) includes: A dynamic sealing ring (41) slidably sleeved on the rotating shaft (1) or the shaft sleeve (2) for cooperating with the static sealing ring member (5) to form a sealing surface (8); A locking ring (42) arranged around the dynamic sealing ring (41) and detachably fixed on the rotating shaft (1) or the shaft sleeve (2) for locking and fixing the dynamic sealing ring (41) on the rotating shaft (1) or the shaft sleeve (2).

3. The active parking seal device for a nuclear main pump according to claim 2, characterized in that, A flange (9) is arranged on the rotating shaft (1) or the shaft sleeve (2), the locking ring (42) has a locking surface (421) axially fitting with the dynamic sealing ring (41) along the rotating shaft (1) or the shaft sleeve (2), and the locking ring (42) is detachably connected to the flange (9) along the axial direction of the rotating shaft (1) or the shaft sleeve (2); The dynamic sealing assembly (4) further includes: a limiting ring (43) sleeved on the rotating shaft (1) or the shaft sleeve (2) and located between the dynamic sealing ring (41) and the flange (9), and fixed on the rotating shaft (1) or the shaft sleeve (2) through the locking ring (42), and an adjusting gap (10) is arranged between the locking ring (42) and the flange (9).

4. The active parking seal device for a nuclear main pump according to claim 3, characterized in that, The limiting ring (43) includes at least two limiting units (431), and the radian of each limiting unit (431) is the same.

5. The active parking seal device for a nuclear main pump according to claim 4, characterized in that, The locking ring (42) includes at least two locking units (422), and the radian of each locking unit (422) is the same.

6. The active parking seal device for a nuclear main pump according to claim 1, characterized in that, A sealing ring (11) is arranged at the sealing surface (8).

7. An active parking seal device for a nuclear main pump according to claim 1, characterized in that, The elastic member (6) includes: A first helical spring (61) with one end abutted against the sealed housing (3) and the other end abutted against the static sealing ring member (5), so that the static sealing ring member (5) always has a tendency to move away from the dynamic sealing ring (41); A second helical spring (62) located inside the inner ring of the first helical spring (61), wherein the central axis of the second helical spring (62) is parallel to the central axis direction of the first helical spring (61).

8. An active parking seal device for a nuclear main pump according to claim 7, characterized in that, The free length of the second helical spring (62) is less than that of the first helical spring (61); when the static seal ring (5) is located on the side away from the dynamic seal ring (41), the second helical spring (62) is at its free length.

9. The active parking seal device for a nuclear main pump according to claim 8, characterized in that, A spring guide post (12) is provided between the static seal ring (5) and the seal housing (3). The axial direction of the spring guide post (12) is parallel to the axial direction of the rotating shaft (1) or the shaft sleeve (2). One end of the spring guide post (12) is fixed to the static seal ring (5), and the other end is slidably connected to the seal housing (3). The second helical spring (62) is sleeved on the spring guide post (12) and has a clearance fit with the spring guide post (12). A limit groove (13) for mating with the outer ring of the first helical spring (61) is provided on the seal housing (3) and / or the static seal ring (5), and the first helical spring (61) has a clearance fit with the limit groove (13).

10. The active parking seal device for a nuclear main pump according to claim 1, characterized in that, The static seal ring (5) is slidably mated between the third seal (14) side and the third seal housing (15). An anti-extrusion seal ring (16) is provided at the sliding fit between the static seal ring (5) and the third seal housing (15). The anti-extrusion seal ring (16) includes a rubber ring (161) and a metal ring (162) located inside the rubber ring (161).

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