Thermally induced phase change liquid metal bearing, ct tube and control method thereof

Abstract

This invention relates to a thermotropic phase change liquid metal bearing, a CT X-ray tube, and a control method thereof. The thermotropic phase change liquid metal bearing includes a fixed shaft, a rotating sleeve, a driving component, a lubricating medium, and a heating assembly. The rotating sleeve is fitted outside the fixed shaft. The driving component, connected to the rotating sleeve, drives the rotating sleeve to rotate relative to the fixed shaft. A gap is formed between the rotating sleeve and the fixed shaft, and the lubricating medium fills the gap. The melting point of the lubricating medium is higher than room temperature and lower than the bearing's preheating operating temperature. The heating assembly is disposed inside the fixed shaft and is used to preheat the lubricating medium, causing it to melt from a solid state to a liquid state. This invention avoids leakage of the lubricating medium during transportation, facilitates transportation, improves its anti-oxidation performance, and significantly improves the yield and long-term storage stability of the X-ray tube.

Description

Technical Field

[0001] This invention belongs to the field of medical diagnostic technology, and particularly relates to a thermo-induced phase change liquid metal bearing, a CT tube, and a control method thereof. Background Technology

[0002] The CT tube is a core precision component of medical CT imaging equipment, and its performance directly determines the imaging accuracy, operational stability, and overall lifespan of medical scans. The internal bearings of the CT tube, serving as the core support for the high-speed rotation of the anode target disk, operate under extreme conditions of high vacuum, strong radiation, instantaneous high temperature, and continuous high-speed rotation. Simultaneously, they must adapt to the equipment's long-term standby, intermittent start-stop, and repeated start-stop scanning modes, placing stringent requirements on the stability, heat dissipation, wear resistance, radiation resistance, and storage and transportation suitability of the bearing lubricating medium. Currently, liquid metal bearing technology is widely used in mid-to-high-end CT tubes, with mainstream industry solutions employing room-temperature liquid metal as the lubricating medium. However, conventional room-temperature liquid metal lubricated bearings still have inherent technical shortcomings in mass production, assembly, storage, transportation, and long-term standby, hindering the finished product qualification rate and long-term service stability of high-end CT tubes.

[0003] Currently, the lubricating medium in the bearings of CT X-ray tubes commonly used in the industry is kept in a constant liquid state at room temperature. When the equipment is working, it can form a fully covered, highly stable lubricating film by relying on the hydrodynamic pressure effect, so as to achieve no hard contact wear of the bearing friction pair. At the same time, it has extremely high heat conduction and heat dissipation efficiency, which can quickly remove the instantaneous high temperature generated by the high-speed rotation of the target plate and X-ray bombardment, effectively suppress the bearing temperature rise, reduce equipment vibration and image artifacts, and significantly improve the upper limit of X-ray tube speed, heat capacity and continuous working capability, perfectly adapting to the extreme working conditions of CT X-ray tubes.

[0004] Because the lubricating medium remains liquid at room temperature, the sealing structure design, processing, and assembly precision of CT tube bearings require extremely high precision. Throughout the entire process of industrial mass production, complete machine packaging, long-distance transportation, warehousing, and clinical standby, problems such as leakage, loss, local segregation, and uneven distribution of the liquid metal medium are highly likely to occur. Simultaneously, the interior of the CT tube is a high-vacuum, sealed environment. During long-term standby, the room-temperature liquid metal medium will slowly react with trace amounts of residual gas and electrode materials inside the cavity, resulting in oxidation, deterioration of the medium components, and abnormal surface tension. This directly leads to deterioration of lubrication performance and a decrease in thermal conductivity. These problems can cause new tubes to experience rotational jamming, abnormal noises upon startup, unstable speed, and abnormal temperature rise after installation, significantly reducing the product's factory pass rate. Furthermore, it can lead to excessively rapid performance degradation and shortened lifespan of in-use tubes, significantly increasing equipment maintenance and replacement costs.

[0005] Therefore, how to provide a thermo-phase change liquid metal bearing and CT tube that can avoid leakage during storage and transportation, facilitate transportation, and prevent oxidation of the lubricating medium is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To solve at least one of the above-mentioned technical problems, the present invention provides a thermally induced phase change liquid metal bearing, comprising: a fixed shaft, a rotating sleeve, a driving component, a lubricating medium, and a heating assembly; The rotating sleeve is fitted outside the fixed shaft; The driving component is connected to the rotating sleeve via a transmission and is used to drive the rotating sleeve to rotate relative to the fixed shaft. A gap is formed between the rotating sleeve and the fixed shaft, and the lubricating medium is filled in the gap; the melting point of the lubricating medium is higher than room temperature and lower than the bearing preheating operating temperature; The heating element is located inside the fixed shaft and is used to preheat the lubricating medium, causing the lubricating medium to melt from a solid state to a liquid state.

[0007] Furthermore, it also includes: a receiving cavity and a flow guide channel; The receiving cavity is located at both axial ends of the outer wall of the fixed shaft and / or the inner wall of the rotating sleeve, and communicates with the gap, for accommodating the phase change volume and thermal expansion volume of the lubricating medium; The guide groove, located on the outer wall of the fixed shaft, is used to guide the lubricating medium into the receiving cavity.

[0008] Furthermore, the receiving cavity includes a first receiving cavity and a second receiving cavity; the outer walls of the fixed shaft are respectively provided with a first groove and a second groove at both axial ends; the inner wall of the rotating sleeve is provided with a third groove corresponding to the first groove and a fourth groove corresponding to the second groove; the groove walls of the first groove and the third groove form the first receiving cavity, and the groove walls of the second groove and the fourth groove form the second receiving cavity; the first receiving cavity, the second receiving cavity, and the gap are interconnected. The guide grooves are evenly arranged along the axial direction on the outer wall of the fixed shaft and are located between the first groove and the second groove.

[0009] Furthermore, the first and second receiving cavities are annular stepped cavities or arc-shaped expanded diameter cavities, with the larger diameter end facing inward and the smaller diameter end facing outward; Furthermore, a sealing assembly is provided at the outward-facing end to seal the gap, the first receiving cavity, and the second receiving cavity.

[0010] Furthermore, the heating assembly includes a heating coil, a temperature sensor, and a controller; Heating coils are disposed within a fixed shaft, comprising several coils spaced apart along the axial direction of the fixed shaft; A temperature sensor is used to monitor the current temperature of the gap, the first receiving cavity, and the adjacent area of ​​the second receiving cavity; The controller is used to start the heating coil to preheat the lubricating medium, causing it to melt from a solid phase into a liquid phase; and to shut down the heating coil when the current temperature exceeds a set threshold.

[0011] Furthermore, the distance between two adjacent heating coils gradually increases from the end of the fixed axis away from the CT tube target plate to the end closer to the CT tube target plate, and / or the heating power of the heating coils gradually decreases from the end of the fixed axis away from the CT tube target plate to the end closer to the CT tube target plate.

[0012] Furthermore, it also includes an anti-adhesion coating; The anti-adhesion coating is applied to the surfaces of the fixed shaft and the rotating sleeve that are in contact with the lubricating medium. The anti-adhesion coating includes any one or more of the following: diamond-like carbon coating, titanium nitride coating, tungsten carbide coating, silicon nitride coating, alumina ceramic coating, and liquid-phobic metal composite coating.

[0013] Furthermore, the lubricating medium is any one or more of gallium-based high-melting-point alloys, indium-based high-melting-point alloys, tin-based high-melting-point alloys, or bismuth-based high-melting-point alloys, and the melting point range of the lubricating medium is 30°C to 80°C.

[0014] In addition, the present invention also provides a CT tube, comprising the thermally induced phase change liquid metal bearing described in any one of the above.

[0015] In addition, the present invention also provides a method for controlling a CT tube, using the above-mentioned CT tube; the method includes: S1: Standby mode: The internal lubricating medium is in a solid state; S2: Start-up preheating: The heating component works, and the internal lubricating medium melts from a solid state to a liquid state; S3: Lubricating medium melting judgment: Detect whether the internal lubricating medium has reached the preset melting temperature. If not, return to step S2; if yes, proceed to step S4. S4: Low-speed unlocking and uniform distribution: The rotating sleeve rotates at low speed and unlocks the CT tube, while the liquid lubricating medium is evenly distributed in the gap. S5: Speed-up operation: The rotating sleeve gradually increases its speed to the target operating speed, and a liquid metal lubricating film is formed in the gap; S6: Operating temperature control: Maintain the lubricating medium within the liquid working temperature range, and the rotating sleeve will rotate normally around the shaft. S7: Stop and reduce speed: The rotating sleeve gradually reduces speed, the heating element maintains short-term heating or heat preservation, and the lubricating medium remains in a liquid or semi-liquid state; S8: Anti-coagulation lock-up: Gradually reduce the heating power of the heating components, and the lubricating medium is cooled in a controlled manner; S9: Resolidation Standby: The lubricating medium resolidifies and returns to step S1.

[0016] This invention provides a thermo-phase change liquid metal bearing, a CT tube, and a control method thereof. The thermo-phase change liquid metal bearing includes a fixed shaft, a rotating sleeve, a lubricating medium, and a heating assembly. The rotating sleeve is fitted outside the fixed shaft, forming a gap with it, and can rotate relative to the fixed shaft. The lubricating medium fills the gap. The melting point of the lubricating medium is higher than room temperature but lower than the bearing's preheating operating temperature. A heating assembly is installed inside the fixed shaft to heat the lubricating medium, causing it to melt from a solid state to a liquid state. The lubricating medium in this application remains solid during storage and transportation. The solid medium significantly reduces the contact area with trace impurities and electrode materials in the vacuum chamber, effectively suppressing problems such as oxidation, component decay, and abnormal surface tension. This avoids deterioration of lubrication performance during long-term storage and standby of the CT tube, significantly improving the yield and product consistency of CT tube mass production. This application solves the problems of failure during room temperature storage and standby, prevents leakage of the lubricating medium during transportation, facilitates transportation, improves its anti-oxidation performance, and significantly improves the yield and long-term storage stability of the finished CT tube. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort. In the drawings, the same parts use the same reference numerals. The drawings are not drawn to scale.

[0018] Figure 1 This is a three-dimensional schematic diagram of an embodiment of a thermally induced phase change liquid metal bearing according to the present invention; Figure 2 This is a schematic diagram from a perspective of an embodiment of a thermally induced phase change liquid metal bearing according to the present invention. Figure 3 for Figure 2 A schematic diagram of the AA cross-section; Figure 4 This is a schematic diagram of the working process of an embodiment of a thermo-induced phase change liquid metal bearing of the present invention.

[0019] Explanation of key component symbols: 100-Thermochromic phase change liquid metal bearing; 110-Fixed shaft; 111-First groove; 112-Second groove; 113-Guide groove; 120-Rotating sleeve; 121-Third groove; 122-Fourth groove; 130-Lubricating medium; 140-Heating assembly; 150-Sealing assembly. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is referred to as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.

[0022] It should also be noted that if the embodiments of the present invention involve directional indications, such as up, down, left, right, front, back, etc., these directional indications are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indications will also change accordingly. Furthermore, if the embodiments of the present invention involve descriptions such as "first," "second," "S1," "S2," "step one," "step two," etc., these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance, or implicitly indicating the number of technical features indicated or the order of method execution. Those skilled in the art will understand that anything that does not violate the inventive concept and does not contradict the inventive points should be included within the scope of protection of the present invention.

[0023] like Figures 1 to 3 As shown, the present invention provides a thermo-induced phase change liquid metal bearing 100, which includes: a fixed shaft 110, a rotating sleeve 120, a driving component, a lubricating medium 130, and a heating assembly 140.

[0024] The rotating sleeve 120 is sleeved on the outside of the fixed shaft 110; The driving component is connected to the rotating sleeve via a transmission and is used to drive the rotating sleeve to rotate relative to the fixed shaft; the driving component can be a motor. A gap is formed between the rotating sleeve 120 and the fixed shaft 110, and the lubricating medium 130 is filled in the gap; the melting point of the lubricating medium 130 is higher than room temperature and lower than the bearing preheating operating temperature; The heating component 140 is disposed inside the fixed shaft 110 and is used to preheat the lubricating medium 130, so that the lubricating medium 130 melts from a solid state to a liquid state.

[0025] Currently, CT tube solid-lubricated bearings mostly use solid metal coatings, graphite, or solid alloy lubricating layers as lubricating media, relying on solid media to achieve static support and low-speed lubrication. These media are stable at room temperature, have no risk of leakage, and can meet the basic requirements for bearing transportation, assembly, and long-term storage. However, their adaptability to different operating conditions is extremely poor. During clinical CT scans, the anode target disk needs to rotate at high speeds of tens of thousands of revolutions per minute, while X-ray bombardment generates a large amount of instantaneous heat, causing a rapid rise in the bearing area temperature. At this time, solid lubricating media suffer from low thermal conductivity, high frictional loss, and easy peeling failure at high temperatures. They cannot form a continuous and uniform lubrication and heat dissipation film, and the bearing raceway and balls are prone to dry friction wear and localized pitting corrosion. Long-term operation can lead to target disk rotational eccentricity and increased equipment vibration, directly causing a decrease in CT image resolution and an increase in artifacts, seriously affecting the accuracy of medical diagnosis. Furthermore, wear failures can significantly shorten the lifespan of the X-ray tube and increase the maintenance costs of medical equipment.

[0026] To address the issues of high-temperature wear and poor heat dissipation in solid-lubricated bearings, the industry is gradually replacing traditional ball bearings with room-temperature liquid metal-lubricated bearings. These bearings use liquid metal as the lubricating medium, relying on hydrodynamic pressure to form a complete lubricating film, completely avoiding hard metal-to-metal wear. They also possess excellent thermal conductivity and heat dissipation properties, making them suitable for the high-speed, high-temperature, and continuous scanning conditions of CT tubes, effectively improving the tube's operational stability and service life. However, this type of room-temperature liquid lubricating medium has serious storage, transportation, and standby defects, significantly impacting the mass production, long-distance transport, and long-term standby of CT tubes. Because the medium remains in a flowing liquid state at room temperature, the design of the tube bearing sealing structure is extremely difficult. During equipment assembly, long-distance transport, storage, and standby, leakage, loss, and segregation of the liquid medium are highly likely to occur. Meanwhile, the inside of the CT tube is a high vacuum environment. When left undisturbed for a long time, the liquid metal medium is prone to oxidation and deterioration with trace amounts of residual air, which leads to a decrease in the lubrication performance of the medium and abnormal viscosity. This can not only cause pre-installation failure of newly installed tubes and installation malfunctions, but also corrode the precision mating surfaces of bearings, causing problems such as abnormal noises during startup and rotational jamming, which can significantly reduce the pass rate of CT tube products and the reliability of equipment service.

[0027] Compared to existing conventional room-temperature liquid metal lubricated CT ball bearings, this invention breaks through conventional design and provides a thermally induced phase change liquid metal bearing. It adopts a phase change metal lubricating medium that is solid at room temperature and liquefies under working heat, solving the problems of leakage during storage and transportation, oxidation during static placement, and component segregation of traditional liquid metal media. At the same time, it fully retains the excellent working performance of liquid metal bearings, such as high thermal conductivity, high lubricity, high speed resistance, and radiation resistance, giving full play to the dual advantages of solid storage, transportation, and static placement in non-working mode and liquid lubrication in working mode.

[0028] In this embodiment, the present invention provides a thermotropic phase change liquid metal bearing 100, including a fixed shaft 110, a rotating sleeve 120, a drive component, a lubricating medium 130, and a heating component 140. The key to this invention lies in combining a room-temperature solid lubricating medium with a heating component, under the premise of using a liquid metal medium in mid-to-high-end CT bearings to achieve high lubrication requirements. This proposes a thermotropic phase change liquid metal bearing that is solid in non-working mode and liquid in working mode. This technical concept is unprecedented in the field. Specifically, this embodiment fills the gap with the lubricating medium 130, and the melting point of the lubricating medium 130 is higher than room temperature but lower than the bearing preheating working temperature. That is, the lubricating medium 130 of the present invention is a stable solid in the non-working state at room temperature, with a fixed shape and no fluidity. This avoids the problems of leakage, loss, local segregation, and uneven distribution caused by the flow of traditional liquid metal media, greatly reducing the design and processing accuracy requirements of the bearing sealing structure and simplifying the assembly, packaging, and quality inspection processes of the CT tube. Meanwhile, the contact area between the solid medium and trace impurity gases and electrode materials in the vacuum chamber is significantly reduced, effectively suppressing problems such as medium oxidation and deterioration, component decay, and abnormal surface tension. This avoids lubrication performance degradation during long-term storage and standby of the X-ray tube, eliminates factory defects such as abnormal noises during new machine installation, unstable speed, and abnormal temperature rise, and significantly improves the yield and product consistency of CT X-ray tube mass production. This invention solves the problems of failure during room temperature storage and standby, greatly improving the yield and long-term storage stability of the X-ray tube. Before the CT X-ray tube is turned on, it is preheated by a heating component, melting it from a solid to a liquid state. Subsequently, the phase change medium can continue to undergo rapid and precise solid-liquid phase change driven by the X-ray tube's own operating temperature rise, quickly transforming into a uniform liquid metal and forming a complete and stable fluid lubrication film. This fully inherits the advantages of traditional liquid metal bearings, such as low friction coefficient, no hard contact wear, and high thermal conductivity. It can effectively adapt to the high-speed rotation of the anode target disk at tens of thousands of revolutions per minute, quickly remove the instantaneous concentrated heat generated by X-ray bombardment and high-speed friction, suppress local high temperature accumulation in the bearing, reduce vibration and mechanical noise during high-speed operation of the equipment, reduce artifacts in CT scan images, improve imaging resolution and uniformity, and ensure the accuracy of clinical diagnosis.

[0029] Specifically, the lubricating medium 130 in this embodiment can be selected from any one or more of gallium-based high-melting-point alloys, indium-based high-melting-point alloys, tin-based high-melting-point alloys, and bismuth-based high-melting-point alloys. More specifically, the melting point range of the lubricating medium 130 in this embodiment can be selected from 30°C to 80°C, for example, 30°C, 45°C, 50°C, 55°C, or 80°C.

[0030] Specifically, in a preferred embodiment, the lubricating medium 130 comprises: 82% gallium, 10% indium, 6% tin, and 2% copper, with an approximate melting point of 45°C. Alternatively, it comprises: 82% gallium, 10% indium, 6% tin, and 2% silver, with an approximate melting point of 50°C.

[0031] The lubricating medium 130 of this invention employs two precisely proportioned gallium-based multi-element alloy lubricating media. Through precise component ratios, the phase transition temperature is precisely locked, avoiding the shortcomings of traditional phase change materials, such as wide temperature ranges and drifting phase transition critical points. The phase transition thresholds of 45℃ and 50℃ are designed to be adapted to different operating conditions, far exceeding the ambient temperature for equipment storage, transportation, and standby. This ensures that the medium remains a dense and stable solid throughout the entire process of storage, transportation, and idleness, preventing low-temperature liquefaction, localized softening, and leakage. Simultaneously, this phase transition temperature is far below the operating temperature range of the CT tube. After the equipment is started and heated, it can quickly break through the melting point threshold, instantly completing a uniform solid-liquid phase transition without phase transition lag or localized unmelted solid residue. This ensures the formation of a complete lubricating film upon startup, with precise and controllable phase transition temperature, perfectly matching the start-up and shutdown operating thresholds of the CT tube. This solves the technical defect of traditional phase change media's untimely operating condition response.

[0032] The lubricating medium 130 of this invention adopts a multi-element alloy formula with excellent stability and significantly improved anti-oxidation and anti-segregation capabilities, making it suitable for the long-term vacuum service environment of X-ray tubes. This invention precisely incorporates trace amounts of copper and silver metal components into the traditional gallium-indium-tin ternary alloy, optimizing the alloy's metallographic structure. Compared to pure gallium-based or ordinary ternary liquid metal media, it significantly improves the medium's room-temperature solid-state density and anti-oxidation performance. The trace amounts of copper and silver effectively inhibit the slow diffusion and segregation of alloy components in a vacuum environment, avoiding the problems of uneven medium composition and performance degradation caused by long-term static placement. Simultaneously, it forms a stable passivation protective structure on the medium surface, reducing the oxidation and corrosion rate caused by trace amounts of residual vacuum gas and electrode materials. This formula addresses the core pain points of traditional liquid metal media, such as easy oxidation and failure, ensuring consistent lubrication and thermal conductivity even after long-term use.

[0033] The lubricating medium 130 of this invention, formulated as described above, exhibits excellent comprehensive mechanical and thermal conductivity properties, balancing high-speed wear resistance with efficient heat dissipation, making it suitable for extreme CT operating conditions. The gallium indium tin copper and gallium indium tin silver quaternary alloy formulation of the lubricating medium 130 retains the advantages of high-proportion gallium-based alloys, such as ultra-high thermal conductivity and low friction coefficient. Simultaneously, trace amounts of copper and silver doping refine the alloy grains, improving fluid uniformity and film adhesion after phase transition. Under high-speed rotation conditions of tens of thousands of revolutions per minute in the X-ray tube, it can form a more resilient and better-adhered lubricating fluid film with stronger shear resistance and anti-loss capabilities, effectively preventing lubricating film rupture and localized dry friction under high-speed conditions. Furthermore, its excellent thermal conductivity can quickly dissipate concentrated heat from the target plate and bearing friction pair, precisely controlling the X-ray tube's operating temperature rise, eliminating imaging artifacts and equipment vibration caused by heat accumulation, and further enhancing the operational stability of the CT X-ray tube during high-speed, high-load continuous scanning.

[0034] Optionally, the thermochromic phase change liquid metal bearing of this embodiment further includes a receiving cavity and a guide channel. The receiving cavity is disposed at both axial ends of the outer wall of the fixed shaft and / or the inner wall of the rotating sleeve, and communicates with the gap, for accommodating the phase change volume and thermal expansion volume of the lubricating medium. The guide channel is disposed on the outer wall of the fixed shaft for guiding the lubricating medium into the receiving cavity.

[0035] Optionally, such as Figure 3 As shown, the receiving cavity includes a first receiving cavity and a second receiving cavity. In this embodiment, a first groove 111 and a second groove 112 are respectively provided at both axial ends of the outer wall of the fixed shaft 110. A third groove 121 corresponding to the first groove 111 and a fourth groove 122 corresponding to the second groove 112 are provided on the inner wall of the rotating sleeve 120. The first groove 111, the second groove 112, the third groove 121 and the fourth groove 122 are, for example, an annular stepped groove, an arc groove, a rectangular groove or an enlarged diameter cavity.

[0036] Specifically, the walls of the first groove 111 and the third groove 121 enclose a first receiving cavity, and the walls of the second groove 112 and the fourth groove 122 enclose a second receiving cavity. The first and second receiving cavities are connected by a gap, and both the first and second receiving cavities are micro-expansion receiving cavities. While the structure of this receiving cavity appears simple, it provides a significant improvement in the use of the thermotropic phase-change liquid metal bearing of this invention: the first and second receiving cavities, surrounded by the fixed shaft and the rotating sleeve, can accommodate the phase change volume and thermal expansion volume of the lubricating medium 130.

[0037] Optionally, the first and second receiving cavities are arc-shaped or rectangular cavities; preferably, the first and second receiving cavities are annular stepped cavities or arc-shaped expanded-diameter cavities, with the larger diameter end facing inward and the smaller diameter end facing outward, to facilitate the inflow and outflow of liquid lubricating medium from the receiving cavity.

[0038] Specifically, when the lubricating medium 130 is in a solid state, a solid expansion gap is reserved in the first and second accommodating cavities. When the lubricating medium 130 is in a liquid state, it at least fills the gap and forms a liquid metal lubricating film between the fixed shaft 110 and the rotating sleeve 120, ensuring the continuous formation of the dynamic pressure liquid metal lubricating film and preventing "dry-up" startup. Furthermore, the first and second accommodating cavities are connected to the main lubrication area through the gap. When the rotating sleeve is subjected to impact or vibration, the liquid metal can be instantly squeezed into or squeezed out of the first and second accommodating cavities, absorbing pulsating energy, thereby unexpectedly enhancing the dynamic stability of the rotating sleeve rotor system and suppressing the eddying of the liquid metal lubricating film.

[0039] The thermally induced phase change liquid metal bearing 100 in this embodiment is adaptable to the extreme working conditions of the CT tube, ensuring high-precision imaging and long-term operational reliability. When the CT tube is turned on, the temperature rise of the tube itself drives the lubricating medium 130 to quickly and accurately complete the solid-liquid phase change, rapidly transforming it into a uniform liquid metal and forming a complete and stable liquid metal lubricating film. It fully inherits the advantages of traditional liquid metal bearings, such as low friction coefficient, no hard contact wear, and high thermal conductivity. It can effectively adapt to the high-speed rotation of the anode target disk at tens of thousands of revolutions per minute, quickly removing the instantaneous concentrated heat generated by X-ray bombardment and high-speed friction, suppressing local high-temperature accumulation in the bearing, reducing vibration and mechanical noise during high-speed operation of the equipment, reducing CT scan image artifacts, improving imaging resolution and uniformity, and ensuring the accuracy of clinical diagnosis.

[0040] Optionally, in this embodiment, a plurality of guide grooves 113 are evenly spaced along the axial direction on the outer wall of the fixed shaft 110, and the plurality of guide grooves 113 are all located between the first groove 111 and the second groove 112. Optionally, the guide groove 113 is, for example, a herringbone groove. Optionally, in this embodiment, the number of guide grooves 113 is, for example, ten. It should be noted that this embodiment does not limit the number of guide grooves 113, and the specific number of guide grooves 113 can be designed according to actual production needs.

[0041] Specifically, when the lubricating medium 130 is in a liquid state, the guide groove 113 can guide and pump the lubricating medium 130, filling the tiny gaps and forming a continuous and stable lubricating film. After a liquid metal lubricating film is formed between the fixed shaft 110 and the rotating sleeve 120, the liquid metal lubricating film can generate a dynamic pressure bearing effect under the rotation of the rotating sleeve 120 by the driving component and the action of the guide groove 113, thereby achieving a bearing effect on the rotating sleeve 120. That is, when the rotating sleeve rotates at high speed, the guide groove 113 and the gap together form a converging wedge-shaped channel, forcing the incompressible liquid metal to increase its pressure sharply in the flow direction. The resulting strong liquid film pressure is sufficient to "lift" the rotating sleeve, achieving non-contact dynamic pressure bearing, thereby significantly reducing friction and wear. Furthermore, the low viscosity, high fluidity, and excellent thermal conductivity of liquid metal itself ensure the stable formation of the liquid film and rapid heat dissipation at high speeds. Simultaneously, as a phase change material, it melts with increasing temperature to provide lubrication and undergoes a vaporization phase change during localized overheating, utilizing gas volume expansion to generate additional static pressure, further suppressing media leakage. Through a synergistic mechanism of flow guidance, film formation, dynamic pressure bearing, and adaptive phase change regulation, this invention constitutes a highly efficient, stable lubrication system with thermal protection capabilities.

[0042] Optionally, the heating assembly 140 in this embodiment includes multiple heating coils, which are embedded within the fixed shaft 110 and spaced apart along the axial direction of the fixed shaft 110. The multiple heating coils are used to perform segmented heating or segmented temperature control of the lubricating medium 130 in the gap. Optionally, this embodiment may use, for example, four heating coils. It should be noted that this embodiment does not limit the number of heating coils; the specific number of heating coils can be designed according to actual production needs.

[0043] In this embodiment, because the temperature of the thermo-phase change liquid metal bearing near the CT tube target plate is higher during CT tube operation, the spacing between two adjacent heating coils gradually increases from the end of the fixed axis away from the CT tube target plate to the end closer to the CT tube target plate, and / or the heating power of the heating coils gradually decreases from the end of the fixed axis away from the CT tube target plate to the end closer to the CT tube target plate. Specifically, the heating coils near the CT tube target plate are arranged more sparsely, while those far from the CT tube target plate are arranged more densely; or they can be configured such that the heating power of some heating coils near the CT tube target plate is lower, while the heating power of some heating coils far from the CT tube target plate is higher; or both the power of the heating coils and the spacing between two adjacent heating coils can be adjusted simultaneously to better adapt to the CT tube operating conditions.

[0044] Optionally, the heating coil in this embodiment includes an annular heating wire and an electrically insulating and heat-conducting layer wrapped around the annular heating wire. The electrically insulating and heat-conducting layer in this embodiment is, for example, an alumina layer, an aluminum nitride layer, a boron nitride layer, a zirconium oxide layer, or a ceramic composite insulating layer.

[0045] It should be noted that, due to the significant heat generated during the operation of the CT tube target disk, the heating coils near the target end of the thermo-phase change liquid metal bearing are arranged sparsely or with low power to avoid excessive heat accumulation in already high-temperature areas, preventing localized overheating that could lead to material aging, seal failure, or oxidation and deterioration of the liquid metal. Conversely, high-power or dense heating at the far target end ensures that the bearing length remains above the melting point of the liquid metal, preventing solidification blockage or flow obstruction at the far end, thus guaranteeing stable circulation and lubrication of the liquid metal within the bearing clearance. This embodiment, by applying greater heating power or arranging heating coils more densely at the far target end of the bearing, compensates for heat loss at the far end, resulting in a more uniform axial temperature distribution throughout the bearing section. This uniform temperature field reduces thermal stress concentration, minimizes mechanical deformation caused by temperature differences, and gradient heating precisely targets the areas most in need of heat, avoiding redundant heating near the target end. This reduces total heating power and energy consumption while ensuring the temperature of the entire section meets the standards.

[0046] Optionally, the heating assembly further includes multiple temperature sensors, which are arrayed and embedded inside the fixed shaft 110 and spaced apart along the axial direction of the fixed shaft 110, for segmented detection of the temperature in the gap, the first receiving cavity, and the adjacent area of ​​the second receiving cavity.

[0047] Optionally, the thermally induced phase change liquid metal bearing 100 in this embodiment further includes an anti-adhesion coating. The anti-adhesion coating is disposed on the surfaces of the fixed shaft 110 and the rotating sleeve 120 that are in contact with the lubricating medium 130. Specifically, the outer wall of the fixed shaft 110 and the inner surface of the rotating sleeve 120 are both provided with the anti-adhesion coating. This coating reduces the solidification and adhesion of the lubricating medium 130 to the outer wall of the fixed shaft 110 and the inner surface of the rotating sleeve 120 when the lubricating medium 130 is in a solid state, and also reduces the wetting and corrosion of the outer wall of the fixed shaft 110 and the inner surface of the rotating sleeve 120 when the lubricating medium 130 is in a liquid state. This embodiment reduces the wettability of the lubricating medium 130 when it is in a liquid state, thereby forming a uniform liquid metal lubricating film in the gap.

[0048] Optionally, the anti-adhesion coating in this invention may be any one or more of the following: diamond-like carbon coating, titanium nitride coating, tungsten carbide coating, silicon nitride coating, alumina ceramic coating, and liquid-phobic metal composite coating.

[0049] Optionally, such as Figures 1 to 3As shown, in this embodiment, a sealing assembly 150 is provided at one end of the rotating sleeve 120 near the second receiving cavity. The sealing assembly 150 is used to seal the gap, the first receiving cavity, and the second receiving cavity, limiting the axial leakage of the liquid lubricating medium 130. Optionally, in this embodiment, the thermotropic phase change liquid metal bearing 100 also includes a thrust disk sleeved on the fixed shaft 110. In this case, the sealing assembly 150 is located between the thrust disk and the rotating sleeve 120. The thrust disk is fixedly connected to the rotating sleeve 120 and can rotate together with the rotating sleeve 120 along with the sealing assembly 150.

[0050] The sealing assembly 150 includes, for example, at least one of a sealing end cap, a labyrinth seal structure, a high-temperature sealing ring, or a magnetohydrodynamic seal structure.

[0051] Optionally, the heating assembly in this embodiment further includes a controller, wherein the controller is electrically connected to the heating coil, the temperature sensor and the drive component for driving the rotating sleeve 120 to rotate, and the controller is used to control the operation of the heating coil, the temperature sensor and the drive component.

[0052] Specifically, when the thermally induced phase change bearing is started, the controller in this embodiment controls the heating coil to execute a start-up preheating program. When the thermally induced phase change bearing is running, the controller controls the rotation speed of the rotating sleeve 120 driven by the drive component and executes a temperature closed-loop control program on the heating coil by receiving temperature detection from the temperature sensor. Furthermore, when the thermally induced phase change bearing is stopped, the controller controls the drive component to reduce the rotation speed of the rotating sleeve 120 and controls the heating coil to gradually reduce the heating power, so that the lubricating medium 130 is cooled in a controlled manner and an anti-solidification lock-up program is executed.

[0053] In addition, the present invention also provides a CT tube that includes all of the above-mentioned thermo-phase change liquid metal bearings, and therefore has all the beneficial effects of all thermo-phase change liquid metal bearings, which will not be elaborated here.

[0054] like Figure 4 As shown in this embodiment, the present invention also provides a method for controlling a CT tube, which may include the following steps: S1: Standby: The internal lubricating medium is in a solid state. Specifically, when the thermochromic liquid metal bearing is shut down, its internal lubricating medium is in a solid state, and the solid lubricating medium is retained in the gap between the fixed shaft and the rotating sleeve. In a preferred embodiment, it is also retained in the first and second receiving cavities, and the solidification and adhesion between the lubricating medium and the fixed shaft and rotating sleeve are reduced by the anti-adhesion coating on the outer wall of the fixed shaft and the inner surface of the rotating sleeve.

[0055] S2: Start-up Preheating: The heating component operates, and the internal lubricating medium melts from a solid state to a liquid state. Specifically, after receiving the start command, the controller controls the heating coil inside the fixed shaft to operate. Specifically, the heat generated by the annular heating wire in the heating coil is transferred through the electrically insulating heat-conducting layer and the fixed shaft to the gap, the first receiving cavity, and the second receiving cavity, raising the temperature of the lubricating medium inside to the melting point temperature of the lubricating medium, thereby melting the solid lubricating medium into a liquid state.

[0056] S3: Lubricating Medium Melting Determination: The heating component detects whether the internal lubricating medium has reached the preset melting temperature. Specifically, a temperature sensor detects the temperature in different axial regions of the fixed shaft, and the controller determines whether the lubricating medium has reached the preset melting temperature. If it has not reached the preset melting temperature, heating continues through the heating coil, or the heating power of the corresponding region's heating coil is increased. If it has reached the preset melting temperature, i.e., the lubricating medium melts from a solid to a liquid state, then the low-speed unlocking stage is allowed. In this embodiment, the first and second receiving cavities accommodate the increased volume and thermal expansion volume of the lubricating medium when it changes from a solid to a liquid state, and a sealing component prevents axial leakage of the liquid lubricating medium.

[0057] S4: Low-speed unlocking and uniform distribution: The rotating sleeve rotates at a low speed, unlocking the CT tube and simultaneously distributing the liquid lubricating medium evenly within the gap. Specifically, the rotating sleeve in the thermotropic phase-change liquid metal bearing of this embodiment is driven to rotate at a low speed by a controller-controlled drive unit. This low speed range is, for example, 1% to 5% of the rated operating speed; optionally, it is, for example, 1%, 2%, or 5% of the rated operating speed. During the low-speed rotation of the rotating sleeve, the liquid lubricating medium is redistributed within the gap and evenly distributed. In this process, the guide groove can guide and pump the liquid lubricating medium to eliminate localized uneven distribution or adhesion.

[0058] S5: Speed-up Operation: The rotating sleeve gradually increases its speed to the target operating speed, forming a liquid metal lubricating film within the gap. Specifically, once the starting resistance or torque is within the normal range, the rotating sleeve rotates smoothly, and then the drive component drives the rotating sleeve to gradually increase its speed to the target operating speed. Optionally, the target operating speed range is, for example, 3000–12000 r / min, where the target operating speed is, for example, 3000 r / min, 5000 r / min, or 12000 r / min. Further, the liquid metal lubricating medium forms a liquid metal lubricating film between the outer wall of the fixed shaft and the inner surface of the rotating sleeve. This liquid metal lubricating film generates a hydrodynamic bearing effect under the action of the guide groove to support the rotating sleeve.

[0059] S6: Operating Temperature Control: Maintains the lubricating medium within its liquid operating temperature range, allowing the rotating sleeve to rotate normally around the shaft. Specifically, during normal operation, the controller adjusts the output power of each heating coil based on feedback signals from the temperature sensor to maintain the lubricating medium within its liquid operating temperature range. This liquid operating temperature range is, for example, 50℃~150℃; optionally, it can be, for example, 50℃, 100℃, or 150℃.

[0060] S7: Stop and Reduce Speed. After receiving the stop command, the controller gradually reduces the speed of the rotating sleeve by controlling the drive components, while simultaneously controlling the heating coil to maintain short-term heating or heat preservation, so that the lubricating medium remains in a liquid or semi-liquid state during the deceleration process.

[0061] S8: Anti-coagulation lock-up: Gradually reduce the heating power of the heating element to control the cooling of the lubricating medium. Specifically, when the rotating sleeve drops to a preset low speed, the controller controls the drive component to make the rotating sleeve perform low-speed idling, micro-amplitude reciprocating rotation, or micro-vibration, and gradually reduce the heating power of the heating coil to control the cooling of the lubricating medium, reducing the risk of adhesion and lock-up between the fixed shaft and the rotating sleeve during coagulation. Optionally, the preset low speed range is, for example, 0.5% to 3% of the rated operating speed, wherein the preset low speed is, for example, 0.5%, 1%, or 3% of the rated operating speed.

[0062] S9: Resolidification Standby: The lubricating medium resolidifies and returns to step S1. When the temperature drops below the melting point of the lubricating medium, the lubricating medium resolidifies and remains in the gap and the first and second receiving cavities. The thermally induced phase change liquid metal bearing returns to the shutdown standby state.

[0063] The thermally induced phase change liquid metal bearing in this embodiment can extend the service life of the CT tube and reduce equipment maintenance and replacement costs. Traditional room-temperature liquid metal media are prone to performance degradation when left stagnant for extended periods, leading to a continuous decline in the tube's lubrication and heat dissipation capabilities, an accelerated bearing wear rate year by year, and a short tube lifespan with frequent replacements. The lubricating medium of this invention is stable in a solid state at room temperature with no performance degradation. It can maintain its initial medium composition and morphology for a long time when not in operation. After phase change during operation, its lubrication and heat dissipation performance remains stable without degradation, significantly reducing the risk of long-term wear, pitting, and jamming of the bearing friction pairs. This effectively slows down the aging rate of the CT tube, significantly extends its service life, reduces hospital equipment downtime for maintenance and tube replacement costs, and improves the continuity and economic efficiency of medical equipment operation. Meanwhile, the solid-state characteristic of the lubricating medium in the thermo-phase change liquid metal bearing of this invention significantly improves the anti-interference capability during the transportation, hoisting, and installation of the ball tube. It avoids the hidden dangers of medium distribution deviation and local liquid shortage caused by transportation bumps and posture changes of traditional liquid media, and improves the environmental adaptability and batch delivery stability of the product. It has extremely strong industrialization value and market promotion prospects.

[0064] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A thermally induced phase change liquid metal bearing, characterized in that, include: Fixed shaft, rotating sleeve, drive components, lubricating medium, and heating assembly; The rotating sleeve is fitted outside the fixed shaft; The driving component is connected to the rotating sleeve via a transmission and is used to drive the rotating sleeve to rotate relative to the fixed shaft. A gap is formed between the rotating sleeve and the fixed shaft, and the lubricating medium is filled in the gap; the melting point of the lubricating medium is higher than room temperature and lower than the bearing preheating operating temperature; The heating element is located inside the fixed shaft and is used to preheat the lubricating medium, causing the lubricating medium to melt from a solid state to a liquid state.

2. The thermally induced phase change liquid metal bearing according to claim 1, characterized in that, Also includes: Receiving cavity and guide channel; The receiving cavity is located at both axial ends of the outer wall of the fixed shaft and / or the inner wall of the rotating sleeve, and communicates with the gap, for accommodating the phase change volume and thermal expansion volume of the lubricating medium; The guide groove, located on the outer wall of the fixed shaft, is used to guide the lubricating medium into the receiving cavity.

3. The thermally induced phase change liquid metal bearing according to claim 2, characterized in that, The receiving cavity includes a first receiving cavity and a second receiving cavity; the outer walls of the fixed shaft are respectively provided with a first groove and a second groove at both axial ends; the inner wall of the rotating sleeve is provided with a third groove corresponding to the first groove and a fourth groove corresponding to the second groove; the first groove wall and the third groove wall enclose the first receiving cavity, and the second groove wall and the fourth groove wall enclose the second receiving cavity; the first receiving cavity, the second receiving cavity and the gap are interconnected. The guide grooves are evenly arranged along the axial direction on the outer wall of the fixed shaft and are located between the first groove and the second groove.

4. The thermally induced phase change liquid metal bearing according to claim 3, characterized in that, The first and second receiving cavities are annular stepped cavities or arc-shaped expanded diameter cavities, with the larger diameter end facing inward and the smaller diameter end facing outward; Furthermore, a sealing assembly is provided at the outward-facing end to seal the gap, the first receiving cavity, and the second receiving cavity.

5. The thermally induced phase change liquid metal bearing according to claim 1, characterized in that, The heating assembly includes a heating coil, a temperature sensor, and a controller; Heating coils are disposed within a fixed shaft, comprising several coils spaced apart along the axial direction of the fixed shaft; Temperature sensors are used to monitor the current temperature of the gap, the first receiving cavity, and the adjacent area of ​​the second receiving cavity; The controller is used to start the heating coil to preheat the lubricating medium, causing it to melt from a solid phase into a liquid phase; and to shut down the heating coil when the current temperature exceeds a set threshold.

6. The thermally induced phase change liquid metal bearing according to claim 5, characterized in that, The distance between two adjacent heating coils gradually increases from the end of the fixed axis away from the CT tube target plate to the end closer to the CT tube target plate, and / or the heating power of the heating coils gradually decreases from the end of the fixed axis away from the CT tube target plate to the end closer to the CT tube target plate.

7. The thermally induced phase change liquid metal bearing according to claim 1, characterized in that, It also includes an anti-adhesion coating; The anti-adhesion coating is applied to the surfaces of the fixed shaft and the rotating sleeve that are in contact with the lubricating medium. The anti-adhesion coating includes any one or more of the following: diamond-like carbon coating, titanium nitride coating, tungsten carbide coating, silicon nitride coating, alumina ceramic coating, and liquid-phobic metal composite coating.

8. The thermally induced phase change liquid metal bearing according to any one of claims 1 to 7, characterized in that, The lubricating medium is any one or more of gallium-based high-melting-point alloys, indium-based high-melting-point alloys, tin-based high-melting-point alloys, or bismuth-based high-melting-point alloys, and the melting point range of the lubricating medium is 30℃~80℃.

9. A CT X-ray tube, characterized in that, Includes the thermo-induced phase change liquid metal bearing as described in any one of claims 1 to 8.

10. A method for controlling a CT tube, using the CT tube of claim 9; the method comprising: S1: Standby mode: The internal lubricating medium is in a solid state; S2: Start-up preheating: The heating component works, and the internal lubricating medium melts from a solid state to a liquid state; S3: Lubricating medium melting judgment: Detect whether the internal lubricating medium has reached the preset melting temperature. If not, return to step S2; if yes, proceed to step S4. S4: Low-speed unlocking and uniform distribution: The rotating sleeve rotates at low speed and unlocks the CT tube, while the liquid lubricating medium is evenly distributed in the gap. S5: Speed-up operation: The rotating sleeve gradually increases its speed to the target operating speed, and a liquid metal lubricating film is formed in the gap; S6: Operating temperature control: Maintain the lubricating medium within the liquid working temperature range, and the rotating sleeve will rotate normally around the shaft. S7: Stop and reduce speed: The rotating sleeve gradually reduces speed, the heating element maintains short-term heating or heat preservation, and the lubricating medium remains in a liquid or semi-liquid state; S8: Anti-coagulation lock-up: Gradually reduce the heating power of the heating components, and the lubricating medium is cooled in a controlled manner; S9: Resolidation Standby: The lubricating medium resolidifies and returns to step S1.

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