Medium self-lubricating guide bearing of nuclear main pump

Abstract

The utility model provides a medium self-lubricating guide bearing for a nuclear main pump, which comprises a metal outer ring, an inner ring, an inner ring, an outer ring, a bearing chamber and an outer ring, and is characterized in that the outer wall of one end of the metal outer ring is provided with an annular bulge for fixing the metal outer ring in the bearing chamber; the carbon ring is embedded in the metal outer ring through interference fit; the rotating shaft penetrates through the carbon ring, and a gap exists between the outer wall of the rotating shaft and the inner wall of the carbon ring to serve as a flow channel for fluid medium circulation. The at least one flow guide through hole is formed in the metal outer ring and distributed in the circumferential direction of the metal outer ring at intervals; and the flow guide through hole is communicated with the flow channel and a return pipeline connected with the annular bulge to form a medium self-lubricating circulation loop, so that a fluid medium flows to the return pipeline along the flow guide through hole after flowing through the inner wall of the carbon ring along the flow channel. The guide bearing provided by the utility model can bear an overtemperature working condition of 1.1 times of the maximum operating temperature, and has the advantages of simple structure, convenience in disassembly and assembly and durability.

Description

Technical Field

[0001] The utility model belongs to the field of guide bearings for nuclear main pumps, and particularly relates to a nuclear main pump medium self-lubricating guide bearing. Background Technique

[0002] The guide bearing is a key device for bearing the radial force of the rotor. In addition to bearing the axial force, the guide bearing of the nuclear main pump must also bear the high-temperature operating conditions from room temperature to about 350°C. Therefore, the structural design of the guide bearing of the nuclear main pump is very crucial. On the one hand, it is necessary to ensure that the guide bearing still has an interference fit under over-temperature conditions. On the other hand, it is necessary to prevent excessive interference fit from causing stress concentration and difficult fitting. Content of the Utility Model

[0003] The purpose of the utility model is to provide a nuclear main pump medium self-lubricating guide bearing. The structure of the nuclear main pump medium self-lubricating guide bearing can withstand the over-temperature conditions of 1.1 times the highest operating temperature, and at the same time has the advantages of excellent operating performance, simple structure, convenient disassembly and assembly, and durability.

[0004] To achieve the above purpose, the utility model provides a nuclear main pump medium self-lubricating guide bearing for supporting a rotating shaft, which includes: a metal outer ring, the outer wall of one end of which is provided with an annular protrusion for fixing the metal outer ring in a bearing chamber; a carbon ring, which is embedded in the metal outer ring by interference fit; the rotating shaft passes through the carbon ring, and there is a gap between the outer wall of the rotating shaft and the inner wall of the carbon ring as a flow channel for fluid medium to flow through; a plurality of guide through holes, which are arranged in the metal outer ring and are circumferentially spaced apart along the metal outer ring; the guide through holes communicate with the flow channel and a return pipeline connected to the annular protrusion to form a circulating loop for medium self-lubrication, so that the fluid medium flows along the flow channel through the inner wall of the carbon ring and then flows to the return pipeline along the guide through holes.

[0005] Optionally, the diameter range of the guide through holes is 10-18 mm.

[0006] Optionally, the structure of the carbon ring is an integral carbon ring made integrally or composed of several segmented carbon rings.

[0007] Optionally, a groove is provided in the circumferential direction of the annular protrusion, and a sealing ring is arranged in the groove to seal the fluid medium in the guide through holes.

[0008] Optionally, the annular protrusion is integrally formed with the metal outer ring, and the surface of the annular protrusion is coated with a chromium coating.

[0009] Optionally, the number of the guide through holes is not less than 3.

[0010] Optionally, the metal outer ring and the carbon ring mounted in the metal outer ring are suspended in the bearing chamber, and a cavity is formed between the metal outer ring and the carbon ring and the bottom wall of the bearing chamber. Each of the fluid conduction holes communicates with the cavity, and the fluid conduction holes and the flow channel are communicated through the cavity.

[0011] Optionally, the fluid conduction hole includes a first through hole and a second through hole. The first through hole is horizontally arranged in the annular protrusion and is connected to the return pipeline at one end; the second through hole is vertically arranged along the axial direction of the metal outer ring, is connected to the first through hole at one end, and is connected to the cavity at the other end, forming a circulation loop for the self-lubrication of the medium.

[0012] Optionally, the rotating shaft includes a shaft body and a shaft sleeve sleeved on the outer wall of the shaft body. A gap exists between the outer wall of the shaft sleeve and the inner wall of the carbon ring, forming the flow channel.

[0013] In summary, compared with the prior art, a nuclear main pump medium self-lubricating guide bearing provided by the present utility model has the following beneficial effects: by arranging a fluid conduction hole in the metal outer ring to connect the flow channel and the return pipeline, a self-circulation loop of the fluid medium is realized, so that the nuclear main pump medium self-lubricating guide bearing structure of the present utility model can withstand an over-temperature condition of 1.1 times the highest operating temperature; at the same time, by setting the carbon ring as a segmented carbon ring, it is more convenient for installation, preventing the carbon ring from being stuck during installation and reducing the wear of the carbon ring. Description of the Drawings

[0014] Figure 1 is a schematic structural diagram of the nuclear main pump medium self-lubricating guide bearing of the present utility model;

[0015] Figure 2 is a schematic diagram of the assembly and circulation loop of the nuclear main pump medium self-lubricating guide bearing of the present utility model;

[0016] Figure 3 is a schematic diagram of the carbon ring mounting of the nuclear main pump medium self-lubricating guide bearing of the present utility model;

[0017] Figure 4 is a flowchart of the carbon ring mounting of the nuclear main pump medium self-lubricating guide bearing of the present utility model. Detailed Embodiments

[0018] The following will combine the attached drawings in the embodiments of the present utility model Figure 1 ~attached drawings Figure 4 , and will detail the technical solutions, structural features, achieved objectives and effects in the embodiments of the present utility model.

[0019] It should be noted that the accompanying drawings are in a very simplified form and use non-precise scales, solely for the purpose of conveniently and clearly assisting in explaining the purpose of the embodiments of the present utility model, rather than being used to limit the limiting conditions for the implementation of the present utility model. Therefore, they do not have any technical substance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the efficacy that the present utility model can generate and the purpose that can be achieved, should still fall within the scope covered by the technical content disclosed in the present utility model.

[0020] It should be noted that in the present utility model, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements explicitly listed, but also other elements not explicitly listed, or elements inherent to such process, method, article or device.

[0021] The present utility model provides a nuclear main pump medium self-lubricating guide bearing. When in use, the nuclear main pump medium self-lubricating guide bearing is installed in the bearing chamber 4 of the nuclear main pump and is used to support the rotating shaft 3. As Figure 1 and Figure 2 shown, the nuclear main pump medium self-lubricating guide bearing includes: a metal outer ring 1, on the outer wall of one end of which there is a ring-shaped protrusion 101 for fixing the metal outer ring 1 in the bearing chamber 4; a carbon ring 2, which is press-fitted and embedded in the metal outer ring 1 through an interference fit on the mating surface 103 between the outer wall of the carbon ring 2 and the inner wall of the metal outer ring 1; the rotating shaft 3 passes through the carbon ring 2, and there is a gap between the outer wall of the rotating shaft 3 and the inner wall 201 of the carbon ring 2 as a flow channel 211 for the fluid medium to flow through; at least one guiding through-hole 102, which is arranged in the metal outer ring and is circumferentially spaced along the metal outer ring 1; the guiding through-hole 102 communicates the flow channel 211 and a return pipeline 113 connected to the ring-shaped protrusion 101 to form a circulating loop for medium self-lubrication, so that the fluid medium flows along the flow channel 211 through the inner wall 201 of the carbon ring and then flows to the return pipeline 113 along the guiding through-hole 102, and the return pipeline 113 transports the fluid medium back into the guide bearing to complete the circulation of the fluid medium.

[0022] Since the nuclear main pump medium self-lubricating guide bearing provided by the present utility model is used in a nuclear power plant, the metal outer ring 1 is made of 1.4313 martensitic stainless steel material, which has high strength, high corrosion resistance and high temperature resistance, and can withstand the flow of high-temperature and high-pressure media in the nuclear power plant loop system. Further, in this embodiment, a flow-through hole 102 is circumferentially provided on the metal outer ring 1, and the diameter range of the flow-through hole 102 is 10-18 mm. By setting the diameter of the flow-through hole to 10-18 mm, on the one hand, it prevents the flow-through hole 102 from having too small a diameter to hinder the flow of fluid medium, resulting in insufficient flow capacity and inability to form sufficient circulating flow. At the same time, too small a hole diameter also makes the processing difficult and the production cost high; on the other hand, too large a diameter of the flow-through hole 102 will cause insufficient wall thickness of the metal outer ring, which is prone to deformation during the hot sleeve installation process, causing potential safety hazards. Preferably, the diameter of the flow-through hole 102 is 15 mm, and the fluid medium is water, which serves as a lubricating medium and a heat dissipation medium. In other embodiments, the number of the flow-through holes 102 is 3 to increase the flow capacity of the fluid medium, and the specific number of the flow-through holes 102 can be set according to actual heat dissipation requirements, flow requirements and lubrication requirements.

[0023] Further, as Figure 2 shown, the rotating shaft 3 includes a shaft body 31 and a shaft sleeve 32 sleeved on the outer wall of the shaft body 31. There is a gap between the outer wall of the shaft sleeve 32 and the inner wall of the carbon ring 2, forming the flow channel 211, so that the fluid medium can flow along the flow channel 211 to achieve the functions of lubrication and heat dissipation.

[0024] Among them, as Figure 1 and Figure 2 shown, when the nuclear main pump medium self-lubricating guide bearing formed by the inlay of the carbon ring 2 and the metal outer ring 1 is installed in the bearing chamber 4, the metal outer ring 1 and the carbon ring 2 inlaid in the metal outer ring 1 are both suspended in the bearing chamber 4 at the same time, so that a cavity 41 is formed between the metal outer ring 1 and the carbon ring 2 and the bottom wall of the bearing chamber 4. The flow-through holes 102 are all communicated with the cavity 41, and the cavity 41 is used to communicate the flow-through holes 102 and the flow channel 211. Further, as Figure 2 shown, the flow-through hole 102 includes a first through hole 121 and a second through hole 122. The first through hole 121 is horizontally arranged in the annular protrusion 101 and is connected to the return pipeline 113 at one end; the second through hole 122 is vertically arranged along the axial direction of the metal outer ring 1, is connected to the first through hole 121 at one end, and is connected to the cavity 41 at the other end, thereby forming a circulating loop for medium self-lubrication, so that the fluid medium flowing through the inner wall 201 of the carbon ring can flow into the cavity 41 and return to the return pipeline 113 through the flow-through hole 102. The structure is simple and compact, realizing the self-lubrication function of the fluid medium.

[0025] Among them, as Figure 1 shown, a groove 111 is provided in the circumferential direction of the annular protrusion 101, and a sealing ring (such as an O-ring) is arranged in the groove 111 to seal the fluid medium in the flow guide hole 102 and prevent the leakage of the fluid medium.

[0026] Furthermore, as Figure 1 shown, the annular protrusion 101 and the metal outer ring 1 are integrally formed, and the surface of the annular protrusion 101 is coated with a chromium coating 112 to enhance its surface wear resistance and avoid wear caused by repeated disassembly and assembly. Among them, the chromium coating 112 can be formed by surface spraying processes such as electroplating or detonation spraying. Still further, the surface of the chromium coating 112 can be ground to improve the surface finish of the chromium coating 112, which is beneficial to the disassembly and assembly of the self-lubricating guide bearing of the nuclear main pump medium.

[0027] Among them, as Figure 1 shown, the structure of the carbon ring 2 is an integral whole carbon ring; in other embodiments, as Figure 3 shown, the structure of the carbon ring 2 is composed of several stages of segmented carbon rings ( Figure 3 in this case, it is a 3-stage carbon ring, that is, including 3 segmented carbon rings). Compared with the integral carbon ring, the carbon ring 2 composed of several stages of segmented carbon rings is convenient for installation and effectively prevents the carbon ring 2 from being too long and getting stuck on the metal outer ring 1, resulting in the carbon ring 2 being unable to be completely installed in the metal outer ring 1.

[0028] Since the installation of the carbon ring 2 is a key process for the self-lubricating guide bearing of the nuclear main pump, the carbon ring 2 and the metal outer ring 1 are installed by the hot sleeve method. As Figure 3 shown, the metal outer ring 1 is placed in the heat preservation tooling 4, and the heat preservation tooling 4 is used to keep the heated metal outer ring 1 warm to prevent the metal outer ring 1 from cooling and shrinking too fast during the installation process. During the heating process of the metal outer ring 1, a thermocouple 5 is arranged on the surface of the annular protrusion 101 at the top end and the bottom surface of the metal outer ring 1 respectively, for continuously measuring the temperature change of the metal outer ring 1. The carbon ring 2 can be designed as an integral carbon ring or a segmented carbon ring. No matter what kind of design, when the temperature of the metal outer ring 1 reaches the requirement, all the carbon rings 2 should be installed in the metal outer ring 1 at the same time. After the metal outer ring 1 and the carbon ring 2 are cooled and left standing for a period of time, the inner wall 201 of the carbon ring 2 is ground to the finished size.

[0029] Specifically, the present invention also provides a method for installing a carbon ring of a nuclear main pump guide bearing, which is applicable to the self-lubricating guide bearing of the nuclear main pump medium as described above. As Figure 4 shown, it includes the following steps:

[0030] S1. Calculate the theoretical minimum interference δ required for carbon ring installation under the operating conditions min_required ;

[0031] Among them, the operating condition is an over-temperature condition at 1.1 times the highest operating temperature, and the theoretical minimum interference δ min_required The calculation formula of is:

[0032] δ min_required = d f ×(α a - α i )×(1.1×t max - Δ t );

[0033] Among them, the d f is the basic dimension of the mating surface of the carbon ring and the metal outer ring; α a is the linear expansion coefficient of the metal outer ring; α i is the linear expansion coefficient of the carbon ring; t max is the highest operating temperature; Δ t is the ambient temperature;

[0034] S2. Determine the minimum interference δ min and the maximum interference δ max of the carbon ring and the metal outer ring inlay; the minimum interference δ min is greater than the theoretical minimum interference δ min_required ;

[0035] Among them, the determination of the minimum interference δ min and the maximum interference δ max of the carbon ring and the metal outer ring inlay includes: based on the theoretical minimum interference δ min_required and the basic dimension d f of the mating surface of the carbon ring and the metal outer ring, according to the tolerance zone of the tolerance fit of the national standard (such as GB / T 1800.3-1998), determine the fit tolerance between the metal outer ring and the carbon ring; according to the fit tolerance, calculate the minimum interference δ min and the maximum interference δ max .

[0036] Among them, the tolerance zone determines the tightness of the fit: the wider the tolerance zone, the looser the fit; the narrower the tolerance zone, the tighter the fit. In a specific embodiment, if the basic dimension of the metal outer ring 1 is d f1 , the tolerance of the metal outer ring 1 is ±δ1, the basic dimension of the carbon ring 2 is d f2 , the tolerance of the carbon ring 2 is ±δ2, then the dimension range of the metal outer ring 1 is [d f1 - δ1, d f1 + δ1], and the dimension range of the carbon ring 2 is [d f2 - δ2, d f2+δ2], and then obtain the minimum interference δ min =(d f1 -δ1)-(d f2 +δ2), the maximum interference δ max =(d f1 +δ1)-(d f2 -δ2).

[0037] S3. Analyze the stress distribution of the metal outer ring and the carbon ring to check whether the stress of the lower guide bearing meets the requirements under the maximum interference δ max . The calculation formula for the maximum stress is as follows:

[0038]

[0039] Among them, σ max is the maximum stress; P max is the maximum pressure at the mating part under the maximum interference; δ max is the maximum interference; c is the material coefficient; d f is the basic dimension of the mating surface of the carbon ring and the metal outer ring; C a and C i are the rigidity coefficients of the metal outer ring and the carbon ring respectively; E a and E i are the elastic moduli of the metal outer ring and the carbon ring respectively;

[0040] If the stress of the lower guide bearing is less than or equal to the maximum stress under the maximum interference δ max , the stress distribution of the guide bearing meets the requirements; otherwise, the stress distribution of the guide bearing does not meet the requirements, and return to steps S1 - S2 to recalculate and determine the minimum interference δ min and the maximum interference δ max .

[0041] S4. Calculate the fitting temperature t according to the maximum interference δ max and the required clearance Δ for fitting;

[0042] Among them, the calculation formula for the fitting temperature is as follows:

[0043]

[0044] Among them, t is the fitting temperature; δ max is the maximum interference; Δ is the required clearance for fitting; α a is the linear expansion coefficient of the metal outer ring; d f is the basic dimension of the mating surface of the carbon ring and the metal outer ring; Δt is the ambient temperature.

[0045] S5. After obtaining the fitting temperature t, determine the number of segmented levels of the carbon ring according to the carbon ring length, the fitting gap, and the cooling shrinkage rate of the metal outer ring, that is, determine how many segmented carbon rings the carbon ring 2 includes. In this embodiment, the number of levels of the carbon ring 2 is 3.

[0046] S6. Measure whether the dimensional change of the heated metal outer ring 1 meets the required fitting gap Δ; if it meets, insert the carbon ring 2 into the metal outer ring 1; if it does not meet, continue heating until the dimensional change of the metal outer ring 1 meets the fitting gap Δ.

[0047] S7. Put the metal outer ring 1, the heat preservation tooling 4, and the thermocouple 5 into the heating device and heat them to the fitting temperature t; in this embodiment, the fitting temperature t does not exceed 475°C.

[0048] S8. Gradually insert the carbon ring 2 into the metal outer ring 1 to complete the insertion of all carbon rings 2 at one time; after insertion, press the carbon ring 2 tightly. After the metal outer ring 1 naturally cools and shrinks at room temperature and stands for a period of time (such as 2 weeks), grind the inner wall 201 of the carbon ring to the finished product to complete the fitting of the carbon ring 2.

[0049] In summary, compared with the prior art, the nuclear main pump medium self-lubricating guide bearing provided by the present invention realizes a self-circulation loop of the fluid medium by providing at least one flow guiding hole 102 in the metal outer ring 1 that communicates with the flow passage 211 and the return pipeline 113, enabling the nuclear main pump medium self-lubricating guide bearing structure of the present invention to withstand the over-temperature condition of 1.1 times the highest operating temperature; at the same time, by setting the carbon ring 2 as a segmented carbon ring, it is more convenient for installation, preventing the carbon ring 2 from being stuck during installation and reducing the wear of the carbon ring 2. Further, through the carbon ring fitting method, the fitting of the carbon ring 2 and the metal outer ring 1 can be realized more accurately, ensuring the fitting accuracy of the two and avoiding the problems of stress concentration and difficult fitting caused by excessive interference.

[0050] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art read the above content, various modifications and substitutions to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A medium self-lubricating guide bearing for a nuclear main pump, which is used to support a rotating shaft, is characterized in that Comprising: A metal outer ring, on the outer wall of one end of which there is an annular protrusion for fixing the metal outer ring in a bearing chamber; A carbon ring, which is embedded in the metal outer ring by interference fit; the rotating shaft passes through the carbon ring, and there is a gap between the outer wall of the rotating shaft and the inner wall of the carbon ring as a flow channel for the fluid medium to flow through; A plurality of fluid guiding through holes, which are arranged in the metal outer ring and are circumferentially spaced along the metal outer ring; Each of the fluid guiding through holes communicates with the flow channel and a return pipeline connected to the annular protrusion, forming a circulating loop for medium self-lubrication, so that the fluid medium flows along the flow channel through the inner wall of the carbon ring and then flows to the return pipeline along the fluid guiding through holes.

2. The self-lubricating guide bearing for the nuclear main pump according to claim 1, wherein The diameter range of the fluid guiding through holes is 10-18 mm.

3. The self-lubricating guide bearing for the nuclear main pump according to claim 1, wherein The structure of the carbon ring is an integral carbon ring made integrally or composed of several stages of segmented carbon rings.

4. The self-lubricating guide bearing for the nuclear main pump according to claim 1, characterized in that, A groove is provided in the circumferential direction of the annular protrusion, and a sealing ring is arranged in the groove to seal the fluid medium in the fluid guiding through holes.

5. The self-lubricating guide bearing for the nuclear main pump according to claim 1, characterized in that, The annular protrusion is integrally formed with the metal outer ring, and a chromium coating is applied on the surface of the annular protrusion.

6. The self-lubricating guide bearing for the nuclear main pump according to claim 1, characterized in that, The number of the fluid guiding through holes is not less than 3.

7. The self-lubricating guide bearing for the nuclear main pump according to claim 1, characterized in that, The metal outer ring and the carbon ring embedded in the metal outer ring are suspended in the bearing chamber, and a cavity is formed between the metal outer ring and the carbon ring and the bottom wall of the bearing chamber. Each of the fluid guiding through holes communicates with the cavity, and the fluid guiding through holes and the flow channel are communicated through the cavity.

8. The self-lubricating guide bearing for the nuclear main pump according to claim 7, wherein, The fluid guiding through hole includes a first through hole and a second through hole. The first through hole is horizontally arranged in the annular protrusion and is connected to the return pipeline at one end; the second through hole is vertically arranged along the axial direction of the metal outer ring, is connected to the first through hole at one end, and is connected to the cavity at the other end, forming the circulating loop for medium self-lubrication.

9. The self-lubricating guide bearing for the nuclear main pump according to claim 1, characterized in that, The rotating shaft includes a shaft body and a shaft sleeve sleeved on the outer wall of the shaft body. There is the gap between the outer wall of the shaft sleeve and the inner wall of the carbon ring, forming the flow channel.

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