Enhanced heat conduction lubrication type ball bearing for X-ray tube and CT (Computed Tomography) bulb tube

Abstract

The invention provides an enhanced heat conduction lubrication type ball bearing for an X-ray tube and a CT bulb tube. The enhanced heat conduction lubrication type ball bearing comprises a bearing sleeve, a sealing end cover, a bearing raceway, a fixing shaft, a sealing baffle and a ball. A bearing cavity for accommodating the bearing raceway is formed in the bearing sleeve, the bearing cavity is filled with liquid metal, gaps among the bearing raceway, the balls and the fixed shaft are filled with the liquid metal, and the fixed shaft is filled with a flowing heat dissipation medium; the two ends of the bearing sleeve are a closed end and an open end respectively, a sealing step is arranged at the open end, movable sealing grooves are formed in the end face of the sealing step and the end face of the sealing end cover, each movable sealing groove comprises two flow channels intersecting at an acute angle, and a sealing groove and a backflow hole communicated with the movable sealing grooves and the sealing groove are formed in the sealing end cover. The anode assembly has good lubricity, heat dissipation capacity and conductivity, the operation stability is improved, the service life is prolonged, and the heat dissipation power of the anode assembly is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of X-ray tubes, and particularly to an enhanced heat-conducting lubricating ball bearing for an X-ray tube and a CT tube equipped with the enhanced heat-conducting lubricating ball bearing. Background Art

[0002] The X-ray tube is a key component in medical devices such as X-ray machines and CT machines. The X-ray tube mainly includes a cathode assembly and an anode assembly both in an ultra-high vacuum closed environment. The anode assembly includes a rapidly rotating anode target disc and an anode bearing for supporting the anode target disc. When the X-ray tube is normally exposed, a current is applied to the filament of the cathode assembly to generate an electron beam. The electron beam generated by the filament of the cathode assembly is accelerated by the strong electric field between the cathode assembly and the anode assembly and bombards the anode target disc of the anode assembly. A very small part of the electron kinetic energy is converted into X-rays, and the remaining most of the energy is deposited on the rapidly rotating anode target disc in the form of heat. The anode target disc rotates at high speed to bear the energy bombarded by the electron beam. Therefore, the temperature of the anode target disc in the working state can reach above 1200°C, and a considerable part of the heat of the anode target disc is transferred to the outside of the X-ray tube in the form of heat conduction through the anode bearing. Then the temperature of the anode bearing in the working state can reach above 300°C, so it is required that each part of the anode bearing has good high-temperature performance. In addition, the anode assembly of the X-ray tube maintains its equipotential state through the anode bearing, so it is required that the anode bearing has good electrical conductivity. At the same time, it is also required that the anode bearing has good lubricity to avoid the failure of the anode bearing. However, since a high potential difference is required between the cathode assembly and the anode assembly when the X-ray tube works, which can exceed 140 KV at most, it is required that each component in the X-ray tube is in an ultra-high vacuum environment to maintain its insulation performance, and the working vacuum degree is generally better than 10 -6 Pa. Therefore, the bearing lubricant that is not suitable for the ultra-high vacuum environment is not suitable for the anode bearing either, which also limits the performance of the anode bearing.

[0003] Currently, the anode bearings in X-ray tubes mainly have two forms: rolling bearings and sliding bearings.

[0004] The liquid hydrodynamic sliding bearing based on a liquid metal lubricating medium composed of several low-melting-point, low-vapor-pressure, and good-conductivity metals such as gallium, tin, and indium has the characteristics of stable operation, good lubricating performance and heat-conducting performance, and high load-carrying capacity, and has been widely used in mainstream high-end X-ray tubes at home and abroad. However, due to the complex manufacturing process of the liquid hydrodynamic sliding bearing, its cost is high, and it also has problems such as instability at low speeds and erosion of the bearing surface by the liquid metal, which also restricts its performance.

[0005] Ball bearings have advantages such as a relatively simple manufacturing process and high low-speed stability, and they are still widely used in X-ray tubes with relatively low power and low rotational speed. However, the existing ball bearings used in X-ray tubes have many defects: 1. The mechanical vibration generated by the high-speed rotation of the anode target disk is transmitted to the rotating shaft through rigid balls and finally to the tube sleeve component, resulting in significant noise in the X-ray tube using ball bearings. 2. The harsh working conditions inside the X-ray tube, such as ultra-high vacuum, relatively high temperature, high voltage, and high cleanliness, lead to the lubrication of ball bearings mainly relying on solid metal coatings. However, the solid metal coatings have poor wear resistance and lubrication performance far lower than traditional lubricants such as grease. As a result, the lubrication between the balls and raceways of the ball bearings is insufficient, and the balls and raceways are severely worn during long-term high-speed and high-temperature operation, which further causes the failure of the ball bearings and leads to the scrapping of the X-ray tube. 3. The anode bearing of the X-ray tube undertakes a considerable part of the heat dissipation of the anode target disk, but the point contact between the balls and raceways of the ball bearing weakens its heat dissipation capacity, thus limiting the exposure power and continuous exposure duration of the X-ray tube. 4. The anode assembly of the X-ray tube maintains the equipotential between the anode target disk and the anode electrode through the anode bearing. Therefore, a non-conductive coating with poor wear resistance cannot be plated on the balls or raceways. The point contact structure between the balls and raceways and the solid lubricating coating on the balls increase the resistance of the anode assembly and have an adverse effect on the electrical performance of the X-ray tube.

[0006] Based on the above problems, liquid metal ball bearings have emerged on the existing market.

[0007] Prior art 1: The Chinese invention patent application with the application number 202111619009.7 discloses a sealed liquid metal ball bearing, which seals the liquid metal through a rubber sealing ring. The rubber sealing ring is preferably a fluororubber sealing ring. However, the currently commonly used rubber sealing rings have problems such as poor high-temperature resistance, easy aging, and high outgassing rate in a vacuum environment, and are basically not used as sealing materials in X-ray tubes. Therefore, this sealed liquid metal ball bearing is not suitable for X-ray tubes.

[0008] Prior art 2: The Chinese utility model patent with the application number 201821181836.6 discloses a high-heat-dissipation medical X-ray tube with an internally cooled ball bearing, which improves the thermal conductivity of the ball bearing by setting a hollow shaft sleeve to directly cool the cooling oil inside the shaft sleeve. However, it does not fundamentally solve the problems of poor thermal conductivity and electrical conductivity caused by the point contact between the balls and raceways of the ball bearing used in X-ray tubes, and poor bearing lubrication. Summary of the Invention

[0009] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide an enhanced heat-conducting and lubricating ball bearing for X-ray tubes, which has good heat conductivity, electrical conductivity, and lubricity.

[0010] To achieve the above object, the present invention provides a heat-enhanced and lubricated ball bearing for an X-ray tube. The heat-enhanced and lubricated ball bearing includes a bearing sleeve and a sealing end cover that are both rotatably arranged and fixedly connected, at least one bearing race fixedly arranged in the bearing sleeve, a fixed shaft partially extending into the bearing sleeve, and a sealing baffle fixed to the outer periphery of the fixed shaft. The bearing race is rotatably assembled around the outer periphery of the fixed shaft through at least one ring of balls; The bearing sleeve is used to be fixed to the anode target disc of the X-ray tube. A bearing chamber for accommodating the bearing race is provided in the bearing sleeve. The bearing chamber is filled with liquid metal, so that the gaps between the bearing race, the balls and the fixed shaft are filled with liquid metal. At least a part of the fixed shaft extends into the bearing sleeve, and a heat dissipation hole filled with a flowing heat dissipation medium is provided in the fixed shaft; Both ends of the bearing sleeve are a closed end and an open end respectively, and a sealing step is provided at the open end. The sealing end cover seals the open end. The sealing baffle is arranged in the open end and distributed between the sealing step and the sealing end cover. There are gaps between the bearing sleeve and the sealing baffle, between the sealing baffle and the sealing end cover, and between the sealing end cover and the fixed shaft. Multiple circumferentially spaced dynamic sealing grooves are provided on the end face of the sealing step facing the sealing baffle and on the end face of the sealing end cover facing the sealing baffle. The dynamic sealing groove includes two flow channels intersecting at an acute angle. At least one sealing groove is provided on the inner wall of the sealing end cover, and a return hole communicating the dynamic sealing groove and the sealing groove is provided in the sealing end cover.

[0011] Further, the liquid metal is a gallium-based metal.

[0012] Further, the dynamic sealing groove is a herringbone groove, or a figure-eight groove, or a V-shaped groove.

[0013] Further, the bearing race is installed into the bearing chamber through the open end. A positioning step is provided on the inner wall of the bearing sleeve near the closed end, and a positioning snap ring is fixedly arranged on the inner wall of the bearing sleeve near the open end. The positioning step and the positioning snap ring respectively abut against both ends of the bearing race.

[0014] Further, a magnetic fluid is provided in the sealing groove.

[0015] Further, the groove depth of the dynamic sealing groove is 10 - 30 μm.

[0016] Further, the gap between the bearing sleeve and the sealing baffle is 10 - 30 μm, the gap between the sealing baffle and the sealing end cover is 10 - 30 μm, and the gap between the sealing end cover and the fixed shaft is 10 - 60 μm.

[0017] Further, there are three sealing grooves in the sealing end cover. The three sealing grooves are spaced along the axial direction of the fixed shaft. The diameters of the three sealing grooves increase in sequence along the direction close to the sealing baffle. The return hole communicates with the sealing groove closest to the sealing baffle among the three sealing grooves. There are 2 - 8 return holes, which are evenly distributed along the circumferential direction of the sealing groove.

[0018] Further, the materials of the bearing sleeve and the sealing end cover are both molybdenum, molybdenum alloy, nickel, or nickel alloy; The materials of the bearing raceway and the fixed shaft are both molybdenum; or the materials of the bearing raceway and the fixed shaft are both nickel - based metals, and an erosion - resistant layer is provided on the surface. The material of the erosion - resistant layer is molybdenum, niobium, tungsten, carbide, or nitride; The material of the ball is silicon nitride, aluminum oxide, zirconia, or silicon carbide; or the material of the ball is a metal with a Rockwell hardness higher than 60, and a non - metallic wear - resistant coating is provided on the surface.

[0019] The present invention also provides a CT tube, which includes a metal tube shell, a cathode assembly hermetically installed at one end of the metal tube shell, and an anode assembly hermetically installed at the other end of the metal tube shell. The anode assembly includes an anode target disc, a rotor assembly, and the enhanced heat - conducting lubricating type ball bearing as described above. The bearing sleeve is fixed to the anode target disc, the sealing end cover is fixed to the rotor assembly, and the fixed shaft is fixed to the metal tube shell.

[0020] Further, the anode target disc includes a target disc main body, a target disc track fixed on the front surface of the target disc main body facing the cathode assembly, and a target disc back body fixed on the back of the target disc main body facing away from the cathode assembly. An axially extending target disc heat - dissipation shaft section is provided on the inner circumference of the target disc main body. The target disc heat - dissipation shaft section is wrapped around the outer circumference of the bearing sleeve and is in surface - contact fit with each other.

[0021] As described above, the enhanced heat - conducting lubricating type ball bearing and the CT tube for an X - ray tube involved in the present invention have the following beneficial effects.

[0022] 1. In the enhanced heat-conducting and lubricating ball bearing involved in the present application, through the dynamic sealing groove on the sealing step end face of the bearing sleeve, the dynamic sealing groove on the end face of the sealing end cover, and the sealing groove inside the sealing end cover, the liquid metal is reliably sealed inside the enhanced heat-conducting and lubricating ball bearing, realizing the introduction of liquid metal as a heat-conducting and lubricating medium in the enhanced heat-conducting and lubricating ball bearing, effectively preventing the liquid metal from leaking to the outside of the bearing chamber and the sealing end cover, and effectively realizing the stable operation of the enhanced heat-conducting and lubricating ball bearing with liquid metal encapsulated inside in the X-ray tube.

[0023] 2. In the enhanced heat-conducting and lubricating ball bearing, the gap between the bearing raceway, the ball, and the fixed shaft is filled with liquid metal. On the one hand, based on the good lubricating performance of the liquid metal, the lubricating conditions between the bearing raceway and the ball are effectively improved, reducing the wear of the bearing raceway and the ball, and improving the operation stability and service life. On the other hand, based on the good heat-conducting performance of the liquid metal, during the operation process, the heat generated by the anode target disc is directly transferred to the bearing sleeve and the bearing raceway, and then the heat is quickly transferred to the hollow fixed shaft through the liquid metal. The heat is introduced into the external heat dissipation system through the heat dissipation medium flowing rapidly inside the fixed shaft, with strong heat dissipation ability, greatly improving the heat dissipation power of the anode assembly containing the enhanced heat-conducting and lubricating ball bearing, providing a reliable guarantee for the high-heat-capacity ball bearing for X-ray tubes with an anode assembly heat capacity greater than 8 MHU, and avoiding the exposure power and continuous exposure duration of the X-ray tube being limited due to heat dissipation problems. In addition, the liquid metal has good electrical conductivity, making the overall enhanced heat-conducting and lubricating ball bearing have good electrical conductivity, thereby reducing the overall resistivity of the anode assembly and improving the electrical stability of the anode assembly. Brief Description of the Drawings

[0024] Figure 1 It is a schematic structural diagram of the enhanced heat-conducting and lubricating ball bearing of the present application.

[0025] Figure 2 It is Figure 1 a cross-sectional view of.

[0026] Figure 3 It is a schematic structural diagram of the bearing sleeve in the enhanced heat-conducting and lubricating ball bearing of the present application.

[0027] Figure 4 It is Figure 3 an enlarged view of circle A of.

[0028] Figure 5 It is Figure 3 a cross-sectional view of.

[0029] Figure 6 It is a schematic structural diagram of the sealing end cover in the enhanced heat-conducting and lubricating ball bearing of the present application.

[0030] Figure 7For Figure 6 Enlarged view of the B circle

[0031] Figure 8 For Figure 6 Cross-sectional view

[0032] Figure 9 Schematic structural diagram of the anode assembly in the CT tube of the present application

[0033] Figure 10 For Figure 9 Cross-sectional view

[0034] Element label description: bearing raceway 10, bearing sleeve 20, bearing chamber 21, closed end 22, open end 23, sealing step 24, positioning step 25, bearing flange part 26, sealing end cover 30, sealing groove 31, return hole 32, fixed shaft 40, heat dissipation hole 41, sealing baffle 50, ball 60, dynamic sealing groove 70, positioning snap ring 80, anode target disc 90, target disc main substrate 91, target disc heat dissipation shaft section 911, target disc flange part 912, target disc track 92, target disc back substrate 93, intermediate spacer ring 110, rotor assembly 120 Specific implementation mode

[0035] The following specific embodiments illustrate the implementation mode of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification

[0036] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in the art to understand and read, and are not used to limit the limited conditions for the implementation of the present invention. Therefore, they do not have any technical substance. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" used in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope within which the present invention can be implemented

[0037] It should also be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as "connected" to another element, it can be directly connected to the other element or can also be indirectly connected to the other element through an intermediate element

[0038] In addition, the descriptions involving "first", "second", etc. in this application are for descriptive purposes only, and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments may be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0039] This application relates to the technical field of X-ray tubes, and particularly relates to an enhanced heat-conducting lubricating ball bearing for an X-ray tube and a CT tube equipped with the enhanced heat-conducting lubricating ball bearing.

[0040] A CT tube is a type of X-ray tube. The CT tube mainly includes a metal tube shell, a cathode assembly, and an anode assembly. Among them, a vacuum environment is formed inside the metal tube shell, so the inner cavity of the metal tube shell is a vacuum cavity, and an X-ray window assembly is installed on the metal tube shell. The cathode assembly is hermetically installed at one end of the metal tube shell. The cathode assembly has a cathode filament for emitting an electron beam, a high-voltage insulating ceramic, and a high-voltage cable. The cathode assembly as a whole is insulated and hermetically connected to the metal tube shell through the high-voltage insulating ceramic. The high-voltage insulating ceramic has good high-voltage insulation performance to achieve high-voltage insulation. The high-voltage cable is used to connect high-voltage electricity to the cathode assembly to make the cathode assembly carry a negative high voltage, usually 140 KV or above. The anode assembly is hermetically installed at the other end of the metal tube shell. As Figure 9 and Figure 10 shown, the anode assembly includes an anode target disk 90, a rotor assembly 120, and an enhanced heat-conducting lubricating ball bearing. The anode target disk 90 is rotatably supported in the metal tube shell through the enhanced heat-conducting lubricating ball bearing. The rotor assembly 120 is connected to the anode target disk 90 through the enhanced heat-conducting lubricating ball bearing. The rotor assembly 120 cooperates with an external stator coil, and the anode target disk 90 is driven by the rotor assembly 120 to rotate at a high speed.

[0041] Particularly, as Figure 1 and Figure 2 and Figure 9 and Figure 10As shown in the figure, the enhanced heat-conducting lubricating ball bearing for an X-ray tube of the present application includes a bearing housing 20, a sealing end cover 30, at least one bearing raceway 10, a fixed shaft 40, and a sealing baffle 50. The bearing housing 20 and the anode target disc 90 in the anode assembly are fixed by several bolts, and the sealing end cover 30 and the rotor assembly 120 in the anode assembly are fixed by several bolts; the two ends of the bearing housing 20 are respectively a closed end 22 and an open end 23, and the sealing end cover 30 is fixed to one side of the open end 23 of the bearing housing 20 by several screws and seals the open end 23, so that both the bearing housing 20 and the sealing end cover 30 are rotatably arranged. The bearing raceway 10 is fixedly arranged in the bearing housing 20 by a tight fit. When there are multiple bearing raceways 10, the multiple bearing raceways 10 are arranged side by side along the axial direction, and an intermediate spacer ring 110 is provided between two adjacent bearing raceways 10. The intermediate spacer ring 110 is fixedly arranged in the bearing housing 20 by a tight fit. The fixed shaft 40 is fixedly welded to the metal tube shell, at least a part of the fixed shaft 40 extends into the bearing housing 20, and the sealing baffle 50 is fixed to the outer periphery of the fixed shaft 40, so that both the fixed shaft 40 and the sealing baffle 50 are fixedly arranged. The bearing raceway 10 is rotatably assembled around the outer periphery of the fixed shaft 40 by at least one ring of balls 60. In this way, the entire anode assembly is hermetically connected to the metal tube shell through the fixed shaft 40.

[0042] Furthermore, as Figures 1 to 5 shown, the bearing housing 20 is a hollow structure with one end open. A bearing chamber 21 for accommodating the bearing raceway 10 is provided in the bearing housing 20. The bearing chamber 21 communicates with its open end 23. The bearing raceway 10 is loaded into the bearing chamber 21 through the open end 23 of the bearing housing 20. The bearing chamber 21 is filled with liquid metal. Then, the liquid metal coats the bearing raceway 10, the balls 60, and the fixed shaft 40 in the bearing chamber 21, so that the gaps between the bearing raceway 10, the balls 60, and the fixed shaft 40 are filled with liquid metal; when there are gaps between the bearing housing 20 and the bearing raceway 10 due to machining errors, these gaps are also filled with liquid metal. The fixed shaft 40 is a hollow structure, and heat dissipation holes 41 are provided in the fixed shaft 40. The heat dissipation holes 41 at least extend into the part of the fixed shaft 40 that extends into the bearing housing 20. Then, at least a part of the heat dissipation holes 41 extends into the bearing housing 20, and the heat dissipation holes 41 are filled with flowing heat dissipation medium. The end of the fixed shaft 40 extending out of the bearing housing 20 is connected to an external heat dissipation system. The bearing housing 20, the bearing raceway 10, the liquid metal, and the fixed shaft 40 constitute an anode heat dissipation structure.

[0043] Furthermore, as Figure 1 and Figure 2As shown, the bearing sleeve 20 is provided with a sealing step 24 at the open end 23, and the sealing baffle 50 is embedded in the open end 23 of the bearing sleeve 20; in the axial direction of the enhanced heat-conducting and lubricating ball bearing, the sealing baffle 50 is located between the sealing step 24 of the bearing sleeve 20 and the sealing end cover 30. There are gaps between the bearing sleeve 20 and the sealing baffle 50, between the sealing baffle 50 and the sealing end cover 30, and between the sealing end cover 30 and the fixed shaft 40, ensuring the smoothness of the rotational movement of the bearing sleeve 20 and the sealing end cover 30 relative to the sealing baffle 50 and the fixed shaft 40. As Figure 3 and Figure 4 shown, on the end face of the sealing step 24 facing the sealing baffle 50, a plurality of circumferentially spaced dynamic sealing grooves 70 are formed, and the dynamic sealing grooves 70 include two flow channels intersecting at an acute angle. As Figures 6 to 8 shown, on the end face of the sealing end cover 30 facing the sealing baffle 50, a plurality of circumferentially spaced dynamic sealing grooves 70 are also formed, and the dynamic sealing grooves 70 include two flow channels intersecting at an acute angle. At the same time, at least one sealing groove 31 is formed on the inner wall of the sealing end cover 30, the sealing grooves 31 are distributed on the outer peripheral side of the fixed shaft 40, and a return hole 32 communicating the dynamic sealing grooves 70 and the sealing grooves 31 is provided in the sealing end cover 30. The fixed shaft 40, the sealing step 24, the sealing baffle 50, and the sealing end cover 30 form a dynamic sealing structure.

[0044] When the CT tube with the enhanced heat-conducting and lubricating ball bearing in this application is operating, the electron beam emitted by the cathode filament is accelerated by the electric field between the cathode assembly and the anode assembly, forming an electron beam with higher energy and bombarding the anode target disc 90. A small part of the electron kinetic energy is converted into X-rays and emitted from the X-ray window assembly on the metal tube shell, and the remaining most of the energy is deposited on the high-speed rotating anode target disc 90 in the form of heat. The heat on the anode target disc 90 is directly transferred to the enhanced heat-conducting and lubricating ball bearing. In the enhanced heat-conducting and lubricating ball bearing, since the bearing raceway 10 is tightly fitted and fixed in the bearing sleeve 20, and the gap between the bearing raceway 10, the ball 60, and the fixed shaft 40 is filled with liquid metal, based on the good heat-conducting performance of the liquid metal, the heat generated by the anode target disc 90 is directly transferred to the bearing sleeve 20 and the bearing raceway 10, and then the heat is quickly transferred to the hollow fixed shaft 40 through the liquid metal, and the heat is introduced into the external heat dissipation system through the heat dissipation medium flowing rapidly in the fixed shaft 40. Therefore, the enhanced heat-conducting and lubricating ball bearing involved in this application has extremely strong heat dissipation ability, greatly improving the heat dissipation power of the anode assembly, providing a reliable guarantee for the X-ray tube with a high heat capacity ball bearing whose anode assembly has a heat capacity greater than 8 MHU, avoiding the exposure power and continuous exposure duration of the CT tube being limited due to heat dissipation problems, and improving the output power of the CT tube and the X-ray tube.

[0045] Furthermore, the gap among the bearing raceway 10, the ball 60, and the fixed shaft 40 is filled with liquid metal. The liquid metal has good lubrication performance, effectively improving the lubrication condition between the bearing raceway 10 and the ball 60, ensuring sufficient lubrication between the bearing raceway 10 and the ball 60, reducing the noise of the CT tube and X-ray tube equipped with this enhanced heat-conducting and lubricating ball bearing, reducing the wear of the bearing raceway 10 and the ball 60, and improving the running stability and service life of the enhanced heat-conducting and lubricating ball bearing. The gap among the bearing raceway 10, the ball 60, and the fixed shaft 40 is filled with liquid metal. The liquid metal has good electrical conductivity, making the entire enhanced heat-conducting and lubricating ball bearing have good electrical conductivity, thereby reducing the overall resistivity of the anode assembly and improving the electrical stability of the anode assembly. At the same time, due to the sufficient lubrication and electrical conductivity between the bearing raceway 10 and the ball 60 through the liquid metal, the surfaces of the bearing raceway 10 and the ball 60 can be coated with a non-metallic wear-resistant coating, or the wear-resistant non-metallic bearing raceway 10 and ball 60 can be directly used, enhancing the wear-resistant performance of the bearing raceway 10 and the ball 60 and significantly reducing the resistance of the anode assembly, thereby improving the service life and overall performance of the enhanced heat-conducting and lubricating ball bearing.

[0046] Particularly, during the operation of the enhanced heat-conducting and lubricating ball bearing in this application, a dynamic sealing structure composed of a fixed shaft 40, a sealing step 24, a sealing baffle 50, and a sealing end cap 30 dynamically seals the liquid metal in the bearing chamber 21, reliably seals the liquid metal within the enhanced heat-conducting and lubricating ball bearing, effectively prevents the liquid metal from leaking to the outside of the bearing chamber and the sealing end cap 30, enables the enhanced heat-conducting and lubricating ball bearing to reliably introduce the liquid metal as a heat-conducting, lubricating, and conductive medium, improves the heat dissipation capacity, lubricating performance, and conductive performance of the enhanced heat-conducting and lubricating ball bearing, and effectively realizes the stable operation of the enhanced heat-conducting and lubricating ball bearing with liquid metal encapsulated inside in the X-ray tube. Moreover, the enhanced heat-conducting and lubricating ball bearing in this application has a ball bearing structure, with a simple manufacturing process and low cost. The principle of dynamic sealing is as follows: The end face of the sealing step 24 and the dynamic sealing grooves 70 thereon, the end face of the sealing end cap 30 and the dynamic sealing grooves 70 thereon, the sealing baffle 50, and the filled liquid metal form two hydrodynamic thrust bearings, providing the radial thrust of the anode assembly shafting. During high-speed rotation, the sealing baffle 50 blocks most of the liquid metal in the bearing chamber 21 within the bearing chamber 21; at the same time, the bearing sleeve 20, the sealing baffle 50, and the sealing end cap 30 all rotate at high speed. Based on the hydrodynamic effect, this part of the liquid metal leaking between the sealing step 24 and the sealing baffle 50, and between the sealing baffle 50 and the sealing end cap 30 flows in the dynamic sealing grooves 70 on the end face of the sealing step 24 and the dynamic sealing grooves 70 on the end face of the sealing end cap 30, and is squeezed to the intersection of the two flow channels of the dynamic sealing groove 70. The intersection of the two flow channels of the dynamic sealing groove 70 is located at the non-end part of the dynamic sealing groove 70, keeping the liquid metal in the middle of the dynamic sealing groove 70 and preventing the liquid metal from flowing into the gap between the sealing end cap 30 and the fixed shaft 40, thereby preventing the liquid metal from leaking to the outside of the bearing sleeve 20; even if some liquid metal leaks into the gap between the sealing end cap 30 and the fixed shaft 40, the liquid metal at this position is sealed by the sealing groove 31 on the inner circumference of the sealing end cap 30. The liquid metal flowing into the sealing groove 31 then flows back to the dynamic sealing groove 70 on the end face of the sealing end cap 30 through the return hole 32, keeping it in the middle of the dynamic sealing groove 70 without leaking out. Finally, the liquid metal is reliably sealed within the bearing sleeve 20.

[0047] Furthermore, during the operation of the CT tube, its metal tube shell and anode assembly are both grounded. Preferably, the metal tube shell of the CT tube is also provided with a secondary electron collector, an anode heat dissipation panel, etc.

[0048] Furthermore, the preferred structure of the anode target disc 90 of the CT tube is as Figure 9 and Figure 10As shown, the anode target disc 90 includes a target disc main substrate 91, a target disc track 92 fixed to the front of the target disc main substrate 91 facing the cathode assembly, and a target disc back substrate 93 fixed to the back of the target disc main substrate 91 facing away from the cathode assembly. The electron beam accelerated by the electric field bombards the target disc track 92 of the anode target disc 90, and most of the remaining energy is deposited on the target disc main substrate 91 of the anode target disc 90 in the form of heat. Based on this, an axially extending target disc heat dissipation shaft section 911 is provided on the inner circumference of the target disc main substrate 91. The target disc heat dissipation shaft section 911 is a cylindrical structure. The target disc heat dissipation shaft section 911 is wrapped around the outer circumference of the bearing sleeve 20 and is in surface contact with each other, increasing the heat conduction area of the heat bridge structure between the anode target disc 90 and the bearing sleeve 20, and more reliably improving the heat dissipation power of the CT tube anode assembly. Preferably, a target disc flange portion 912 is integrally provided at one end of the target disc heat dissipation shaft section 911 away from the target disc track 92, and a bearing flange portion 26 is integrally provided on the outer circumference of the open end 23 of the bearing sleeve 20. The target disc flange portion 912 and the bearing flange portion 26 are fixedly connected by several bolts to realize the fixed connection between the anode target disc 90 and the bearing sleeve 20. In addition, the material of the target disc track 92 is rhenium-tungsten alloy, which improves the efficiency of generating X-rays and has good high-temperature resistance; the material of the target disc main substrate 91 is molybdenum, titanium, zirconium alloy, and the material of the target disc back substrate 93 is graphite, which is beneficial to quickly conduct away the heat generated by the target disc track 92.

[0049] Further, in the enhanced heat-conducting lubricating ball bearing, the fixed shaft 40, the balls 60 and the bearing raceway 10 form a ball bearing assembly. The ball bearing assembly is installed into the bearing chamber 21 through the open end 23 of the bearing sleeve 20; the bearing chamber 21 is a closed structure at both ends. One end of the bearing chamber 21 is closed by the closed end 22 of the bearing sleeve 20, and the other end of the bearing chamber is closed by the sealing end cover 30. After the ball bearing assembly is installed, the axial clearance between the end of the fixed shaft 40 and the closed end 22 of the bearing sleeve 20 is 5 - 30 μm. As Figure 2 and Figure 5 shown, a positioning step 25 is provided on the inner wall of the bearing sleeve 20 near the closed end 22, and a positioning snap ring 80 is fixedly provided on the inner wall of the bearing sleeve 20 near the open end 23. The positioning step 25 and the positioning snap ring 80 respectively abut against both ends of the bearing raceway 10 to axially position the ball bearing assembly.

[0050] Preferably, in the enhanced heat-conducting lubricating ball bearing, the sealing baffle 50 is a metal baffle. The liquid metal is a gallium-based metal with high vapor pressure, excellent heat-conducting and electrical-conducting properties, and a low melting point. The materials of the bearing sleeve 20 and the sealing end cap 30 are both molybdenum, molybdenum alloy, nickel, or nickel alloy with good high-temperature performance and processing performance. The materials of the bearing raceway 10, the intermediate spacer ring 110, and the fixed shaft 40 are all molybdenum, which has good resistance to liquid metal corrosion; or, the materials of the bearing raceway 10, the intermediate spacer ring 110, and the fixed shaft 40 are all nickel-based metals, and an erosion-resistant layer is provided on the surface by coating. The materials of the erosion-resistant layer are metals such as molybdenum, niobium, tungsten, or various carbides, or various nitrides, to improve the liquid metal corrosion resistance of the bearing raceway 10, the intermediate spacer ring 110, and the fixed shaft 40, so that the bearing raceway 10, the intermediate spacer ring 110, and the fixed shaft 40 have a long service life; the thickness of the erosion-resistant layer is 1 - 10 μm. The material of the ball 60 is a ceramic material such as silicon nitride, alumina, zirconia, or silicon carbide, to improve the wear resistance of the ball 60; or, the material of the ball 60 is a metal with a Rockwell hardness higher than 60, and a non-metallic wear-resistant coating is provided on the surface by coating. For example, the ball 60 is high-chromium steel and a non-metallic wear-resistant coating is provided on the surface.

[0051] Preferably, in the enhanced heat-conducting lubricating ball bearing, the depth of the dynamic sealing groove 70 on the end face of the sealing step 24 of the bearing sleeve 20 is 10 - 30 μm, and the depth of the dynamic sealing groove 70 on the end face of the sealing end cap 30 is also 10 - 30 μm. The dynamic sealing groove 70 is a herringbone groove, or a figure-eight groove, or a V-shaped groove. The gap between the end face of the sealing step 24 of the bearing sleeve 20 and the sealing baffle 50 is 10 - 30 μm, the gap between the sealing baffle 50 and the sealing end cap 30 is 10 - 30 μm, and the gap between the sealing end cap 30 and the fixed shaft 40 is 10 - 60 μm.

[0052] Furthermore, as Figures 6 to 8 shown, there are three sealing grooves 31 in the sealing end cap 30. The three sealing grooves 31 are spaced along the axial direction of the fixed shaft 40, and the diameters of the three sealing grooves 31 increase in sequence along the direction close to the sealing baffle 50. The return hole 32 communicates with the sealing groove 31 that is closest to the sealing baffle 50 among the three sealing grooves 31. Preferably, the diameter of the sealing groove 31 is 0.1 - 0.8 mm. There are 2 - 8 return holes 32 opened in the sealing end cap 30, and several return holes 32 are evenly distributed along the circumferential direction of the sealing groove 31.

[0053] Furthermore, a magnetorheological fluid is provided in the sealing groove 31 to more reliably seal the liquid metal.

[0054] In summary, through the dynamic sealing structure formed by the fixed shaft 40, the sealing step 24, the sealing baffle 50 and the sealing end cover 30, the present application reliably seals the liquid metal in the bearing chamber 21, preventing the liquid metal from leaking into the inside of the CT tube and the X-ray tube, and avoiding the leakage of the liquid metal from contaminating the CT tube and the X-ray tube due to the generation of particles or steam caused by the high temperature and high-speed rotation of the enhanced heat-conducting and lubricating ball bearing. This enables the bearing in the anode assembly to reliably introduce liquid metal as a heat-conducting, lubricating and conductive medium on the basis of using a ball bearing, greatly improving the electrical conductivity, heat conductivity and lubrication performance of the bearing in the anode assembly, and ultimately enhancing the performance of the CT tube and the X-ray tube.

[0055] In summary, the present invention effectively overcomes various drawbacks in the prior art and has high industrial utilization value.

[0056] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. An enhanced heat-conducting lubricating type ball bearing for an X-ray tube, characterized in that: The enhanced heat-conducting lubricating ball bearing includes a bearing sleeve and a sealing end cover that are both rotatably arranged and fixedly connected, at least one bearing raceway fixed in the bearing sleeve, a fixed shaft partially extending into the bearing sleeve, and a sealing baffle fixed on the outer periphery of the fixed shaft. The bearing raceway is rotatably assembled on the outer periphery of the fixed shaft through at least one circle of balls; The bearing sleeve is used to be fixed to the anode target disc of the X-ray tube. A bearing chamber for accommodating the bearing raceway is provided in the bearing sleeve. The bearing chamber is filled with liquid metal, so that the gaps between the bearing raceway, the balls, and the fixed shaft are filled with liquid metal. At least a part of the fixed shaft extends into the bearing sleeve and is provided with heat dissipation holes filled with flowing heat dissipation medium; Both ends of the bearing sleeve are a closed end and an open end respectively, and a sealing step is provided at the open end. The sealing end cover seals the open end. The sealing baffle is arranged in the open end and distributed between the sealing step and the sealing end cover. There are gaps between the bearing sleeve and the sealing baffle, between the sealing baffle and the sealing end cover, and between the sealing end cover and the fixed shaft. Multiple circumferentially spaced dynamic sealing grooves are opened on the end surface of the sealing step facing the sealing baffle and on the end surface of the sealing end cover facing the sealing baffle. The dynamic sealing groove includes two flow channels intersecting at an acute angle. At least one sealing groove is opened on the inner wall of the sealing end cover. A return hole communicating its dynamic sealing groove and the sealing groove is provided in the sealing end cover.

2. The enhanced heat-conducting lubricating type ball bearing for an X-ray tube according to claim 1, wherein: The liquid metal is a gallium-based metal.

3. The enhanced heat-conducting lubricating ball bearing for an X-ray tube according to claim 1, wherein: The dynamic sealing groove is a herringbone groove, or a figure-eight groove, or a V-shaped groove.

4. The enhanced heat-conducting lubricating ball bearing for an X-ray tube according to claim 1, characterized in that: The bearing raceway is installed into the bearing chamber through the open end. A positioning step is provided on the inner wall of the bearing sleeve near the closed end, and a positioning snap ring is fixed on the inner wall of the bearing sleeve near the open end. The positioning step and the positioning snap ring respectively abut against both ends of the bearing raceway.

5. The enhanced heat-conducting lubricating ball bearing for an X-ray tube according to claim 1, wherein: Magnetic fluid is provided in the sealing groove.

6. The enhanced heat-conducting lubricating ball bearing for an X-ray tube according to claim 1, characterized in that: The groove depth of the dynamic sealing groove is 10 - 30 μm.

7. The enhanced heat-conducting lubricating ball bearing for an X-ray tube according to claim 1, wherein: The gap between the bearing sleeve and the sealing baffle is 10 - 30 μm, the gap between the sealing baffle and the sealing end cover is 10 - 30 μm, and the gap between the sealing end cover and the fixed shaft is 10 - 60 μm.

8. The enhanced heat-conducting lubricating type ball bearing for an X-ray tube according to claim 1, wherein: There are three sealing grooves in the sealing end cover. The three sealing grooves are axially spaced along the fixed shaft. The diameters of the three sealing grooves increase in sequence along the direction close to the sealing baffle. The return hole communicates with the sealing groove that is closest to the sealing baffle among the three sealing grooves. There are 2 - 8 return holes and they are evenly distributed along the circumference of the sealing groove.

9. The enhanced heat-conducting lubricating ball bearing for an X-ray tube according to claim 1, characterized in that: The materials of the bearing sleeve and the sealing end cover are both molybdenum, molybdenum alloy, nickel, or nickel alloy; The materials of the bearing raceway and the fixed shaft are both molybdenum; or the materials of the bearing raceway and the fixed shaft are both nickel-based metals and an erosion-resistant layer is provided on the surface. The material of the erosion-resistant layer is molybdenum, niobium, tungsten, carbide, or nitride; The material of the ball is silicon nitride, aluminum oxide, zirconium oxide, or silicon carbide; or the material of the ball is a metal with a Rockwell hardness higher than 60 and is provided with a non-metallic wear-resistant coating on the surface.

10. A CT tube, comprising a metal tube shell, a cathode assembly hermetically installed at one end of the metal tube shell, and an anode assembly hermetically installed at the other end of the metal tube shell, wherein the anode assembly includes an anode target disc and a rotor assembly, and is characterized in that: The anode assembly further includes the enhanced heat-conducting lubricating ball bearing according to any one of claims 1-9, the bearing sleeve is fixed to the anode target disc, the sealed end cover is fixed to the rotor assembly, and the fixed shaft is fixed to the metal tube housing.

11. The CT tube according to claim 10, wherein: The anode target disc includes a target disc main substrate, a target disc track fixed on the front surface of the target disc main substrate facing the cathode assembly, and a target disc back substrate fixed on the back of the target disc main substrate facing away from the cathode assembly. An axially extending target disc heat dissipation shaft section is provided on the inner circumference of the target disc main substrate. The target disc heat dissipation shaft section is wrapped around the outer circumference of the bearing sleeve and the two are in surface contact and cooperation.

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