JP2023154827A - Rotary anode x-ray tube - Google Patents

Abstract

To provide a rotary anode X-ray tube that, when the temperature of a sliding bearing is excessively increased, can prevent conduction of heat from an anode target to a bearing surface.SOLUTION: A rotary anode X-ray tube comprises: a cathode that discharges electrons; an anode target that generates X-rays upon receiving the electrons; a sliding bearing that has a rotor extending along a rotation axis, a stationary shaft supporting the rotor, and lubricant held between the rotor and the stationary shaft; and a vacuum envelope. The stationary shaft has a heat radiation part that radiates internal heat to the outside. The rotor has a first heat transfer member that is formed extending along the rotation axis, fixed to the inside of the anode target, and located surrounding the stationary shaft, and a second heat transfer member that is formed extending along the rotation axis, and in contact with an inner face of the first heat transfer member. The coefficient of thermal expansion of the first heat transfer member is larger than the coefficient of thermal expansion of the second heat transfer member.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to rotating anode x-ray tubes.

Generally, medical equipment and industrial equipment that use X-rays to diagnose a subject use an X-ray tube device as an X-ray generation source. As an X-ray tube device, a rotating anode X-ray tube device including a rotating anode X-ray tube (hereinafter also referred to as a "rotating anode X-ray tube") is known.

A rotating anode X-ray tube includes a cathode that emits electrons, an anode target that receives electrons and generates X-rays, and a sliding bearing that includes a rotating body, a fixed shaft, and a lubricant. Most of the energy received from electrons in the anode target is converted into heat, causing the temperature to rise. The heat generated in the anode target is transmitted to the fixed shaft via the bearing surface of the plain bearing, and is exhausted to the outside of the rotating anode X-ray tube via the fixed shaft. It is known that sliding bearings can be protected by using a material with low thermal conductivity for the rotating body.

Japanese Patent Application Publication No. 2000-340148 Japanese Patent Application Publication No. 2012-104391

This embodiment provides a rotating anode X-ray tube that can make maximum use of conduction cooling when the temperature of the plain bearing is within an acceptable range.

A rotating anode X-ray tube according to one embodiment includes a cathode that emits electrons, an anode target that receives the electrons and generates X-rays, and a rotating body that is connected to the anode target and extends along a rotation axis. a fixed shaft rotatably supporting the rotating body; and a lubricant held between the rotating body and the fixed shaft; and the cathode and the anode target. a vacuum envelope that houses the fixed shaft and fixes the fixed shaft, the fixed shaft has a heat dissipation part that radiates internal heat to the outside, and the rotating body extends along the rotational axis. a first heat transfer component that is formed to be fixed inside the anode target and located around the fixed shaft; and a first heat transfer component that is formed to extend along the rotation axis and that contacts the inner surface of the first heat transfer component. a second heat transfer component, wherein the first heat transfer component has a larger coefficient of thermal expansion than the second heat transfer component.

FIG. 1 is a sectional view showing an X-ray tube device according to one embodiment. FIG. 2 is a side view of a portion of the fixed shaft shown in FIG. 1. FIG. FIG. 3 is an enlarged sectional view showing a part of the rotating anode X-ray tube according to the above embodiment, and is a diagram showing a state from when heat is input to the anode target until the anode target is cooled. FIG. 4 is an enlarged sectional view showing a part of a modification of the rotating anode X-ray tube according to the above embodiment.

Embodiments of the present invention will be described below with reference to the drawings. Note that the disclosure is merely an example, and any modifications that can be easily made by those skilled in the art while maintaining the spirit of the invention are naturally included within the scope of the present invention. In addition, in order to make the drawings and explanations clearer, the width, thickness, shape, etc. of each part may be schematically represented compared to the actual state, but this is just an example and the interpretation of the present invention is It is not limited. In addition, in this specification and each figure, the same elements as those described above with respect to the existing figures are denoted by the same reference numerals, and detailed explanations thereof may be omitted as appropriate.

First, the basic concept of the embodiment of the present invention will be explained.
An X-ray tube generates X-rays by colliding electrons generated at a cathode with an anode target at high speed, and the energy that is not converted into X-rays turns into heat, increasing the temperature of the anode target. Since most of the energy becomes heat, the cooling characteristics of the anode target temperature are one of the important characteristics. In a rotating anode X-ray tube that employs a bearing that uses liquid metal as a lubricant (hereinafter referred to as a "rotating anode X-ray tube"), the anode target is Radiation cooling, in which heat is radiated from the surface of the anode, and conduction cooling, in which the heat conducted from the anode target to the plain bearing is cooled by circulating water inside the fixed shaft. Conduction cooling has better cooling efficiency than radiation cooling, but if conduction cooling is promoted and the temperature of the plain bearing rises excessively, it can lead to deterioration of bearing characteristics and, in some cases, cause failures such as rotation stoppage. Become. Therefore, the structure of the rotating anode X-ray tube was decided to maximize the rate of conduction cooling as much as possible to optimize the cooling efficiency, while also suppressing the temperature rise of the plain bearing so as not to impair the bearing characteristics. has been done.

The structure of a conventional rotating anode X-ray tube is such that efficient conduction cooling is suppressed so that the bearing temperature does not rise excessively so as not to impair the bearing characteristics. Therefore, when a rotating anode X-ray tube is actually used, conduction cooling is suppressed even if the temperature of the sliding bearing is within the allowable range, so the cooling efficiency of the anode target is not optimal. There's a problem.

Therefore, in an embodiment of the present invention, this problem is improved, and if the temperature of the sliding bearing is within an allowable range, it is possible to obtain a rotating anode type X-ray tube that can make maximum use of conduction cooling. It is.

FIG. 1 is a sectional view showing an X-ray tube device according to one embodiment.
As shown in FIG. 1, the X-ray tube device includes a rotating anode X-ray tube 1, a stator coil 2 as a coil for generating a magnetic field, and the like. The rotating anode type X-ray tube 1 includes a sliding bearing 3, an anode target 50, a cathode 60, and a vacuum envelope 70. The slide bearing 3 has a fixed shaft 10, a rotating body 20, and a liquid metal LM as a lubricant.

The fixed shaft 10 is formed in a cylindrical shape, extends along the rotation axis a, and has radial bearing surfaces S11a and S11b formed on the outer peripheral surface, and a heat transfer portion 10a. The fixed shaft 10 includes a large diameter portion 11, a first small diameter portion 12, and a second small diameter portion 13. The large diameter portion 11, the first small diameter portion 12, and the second small diameter portion 13 are integrally formed coaxially. The fixed shaft 10 is made of metal such as Fe (iron) alloy or Mo (molybdenum) alloy.

Hereinafter, details of the large diameter portion 11 of the fixed shaft 10 will be explained using FIG. 2. FIG. 2 is a side view showing a part of the fixed shaft 10 shown in FIG. 1. FIG.
As shown in FIG. 2, the large diameter portion 11 has a radial bearing surface S11a, a radial bearing surface S11b, a concave surface S11c, a concave surface S11d, and a concave surface S11e, which are located on the outer peripheral surface. Further, the large diameter portion 11 has a thrust bearing surface S11i at one end and a thrust bearing surface S11j at the other end. The radial bearing surface S11a and the radial bearing surface S11b are each formed on the outer peripheral surface of the large diameter portion 11 over the entire circumference. The concave surface S11c, the concave surface S11d, and the concave surface S11e are each formed on the outer peripheral surface of the large diameter portion 11 over the entire circumference.

The radial bearing surface S11a and the radial bearing surface S11b are spaced apart from each other in the direction along the rotation axis a. The concave surface S11c is located between the radial bearing surface S11a and the radial bearing surface S11b, and is adjacent to each of the radial bearing surface S11a and the radial bearing surface S11b. The concave surface S11d is located beyond the radial bearing surface S11a from the concave surface S11c, and is adjacent to the radial bearing surface S11a. The concave surface S11e is located beyond the radial bearing surface S11b from the concave surface S11c, and is adjacent to the radial bearing surface S11b.

The radial bearing surface S11a has a plain surface Sa and a plurality of pattern parts Pa. The plane surface Sa has a smooth outer peripheral surface. The plurality of pattern parts Pa are formed by recessing the plane surface Sa. Each pattern portion Pa is arranged to extend diagonally in the circumferential direction. The plurality of pattern parts Pa are formed at intervals in the direction along the rotation axis a. Note that the plurality of pattern parts Pa may be connected in the direction along the rotation axis a.

The radial bearing surface S11b has a plain surface Sb and a plurality of pattern parts Pb. The plane surface Sb has a smooth outer peripheral surface. The plurality of pattern parts Pb are formed by recessing the plane surface Sb. Each pattern portion Pb is arranged in a diagonal manner extending in the circumferential direction. The plurality of pattern parts Pb are formed at intervals in the direction along the rotation axis a. Note that the plurality of pattern parts Pb may be connected in the direction along the rotation axis a.

Each pattern portion Pa and each pattern portion Pb are formed as grooves having a depth of several tens of μm. The plurality of pattern parts Pa and the plurality of pattern parts Pb each form a herringbone pattern. Therefore, the radial bearing surfaces S11a and S11b each have an uneven surface, and can scrape in the liquid metal LM, making it easier to generate dynamic pressure due to the liquid metal LM.

Each of the concave surfaces S11c, S11d, and S11e is a smooth outer peripheral surface and a plain surface. The concave surface S11c, the concave surface S11d, and the concave surface S11e are formed to be depressed compared to the radial bearing surface S11a and the radial bearing surface S11b. In other words, in the fixed shaft 10, the outer diameter DO2 of the section where the concave surfaces S11c, S11d, and S11e are formed is smaller than the smallest outer diameter DO1 among the outer diameters of the section where the radial bearing surfaces S11a and S11b are formed.

In the direction perpendicular to the rotation axis a, the gap between the concave surfaces (concave surfaces S11c, S11d, S11e) and the second heat transfer component 22 is the gap between the radial bearing surface S11a (plain surface Sa) and the second heat transfer component 22. It is larger than the gap between the radial bearing surface S11b (plane surface Sb) and the second heat transfer component 22.

The space between the concave surface S11c and the second heat transfer component 22, the space between the concave surface S11d and the second heat transfer component 22, and the space between the concave surface S11e and the second heat transfer component 22 are filled with liquid metal LM. It can function as a reservoir for accommodating. Since the liquid metal LM can be supplied to each of the radial bearing surfaces S11a and S11b from both sides, depletion of the liquid metal LM in the bearing gap can be suppressed.

As shown in FIG. 1, the first small-diameter portion 12 is formed in a cylindrical shape with an outer diameter smaller than that of the large-diameter portion 11, and extends from one end of the large-diameter portion 11. The first small diameter portion 12 is located closer to the rotation axis a than the thrust bearing surface S11i.

The second small diameter portion 13 is formed in a cylindrical shape with an outer diameter smaller than that of the large diameter portion 11, and is formed to extend from the other end of the large diameter portion 11. The second small diameter portion 13 is located closer to the rotational axis a than the thrust bearing surface S11j.

The fixed shaft 10 includes a first bottom surface 10b1, a second bottom surface 10b2, and a heat transfer portion 10a. The second bottom surface 10b2 is located on the opposite side of the first bottom surface 10b1 in the direction along the rotation axis a. In one example, the first bottom surface 10b1 is located in the first small diameter portion 12, and the second bottom surface 10b2 is located in the second small diameter portion 13.

The heat transfer portion 10a extends along the rotation axis a and is open to the first bottom surface 10b1 and the second bottom surface 10b2. The heat transfer section 10a transfers heat to the refrigerant flowing therein by forced convection. The refrigerant is, for example, a cooling liquid L. The cooling rate of the anode target 50 of the rotating anode X-ray tube 1 can be improved by water cooling or oil cooling (insulating oil). Note that the coolant may be air, and the cooling rate of the anode target 50 may be improved by air cooling.

It is preferable that the heat transfer portion 10a be located at least in the region A facing the anode target 50. Thereby, the portion of the fixed shaft 10 to which the heat of the anode target 50 is easily transferred can be cooled.

From the above, the heat transfer section 10a is a heat radiating section that radiates the heat inside the fixed shaft 10. Note that the method for discharging the heat inside the fixed shaft 10 is not limited to using the heat transfer section 10a as a heat dissipation section to transfer heat to the refrigerant. For example, the heat inside the fixed shaft 10 may be released by cooling the first bottom surface 10b1 and the second bottom surface 10b2 with a heat exchanger. In this case, since the first bottom surface 10b1 and the second bottom surface 10b2 serve as heat radiating sections, the rotating anode X-ray tube 1 may be configured without the heat transfer section 10a and the coolant (coolant L).

The rotating body 20 is configured to be rotatable around the fixed shaft 10. The rotating body 20 includes a first heat transfer component 21 , a second heat transfer component 22 , a first stopper 23 , a second stopper 24 , and a cylindrical portion 25 .

The first heat transfer component 21 extends along the rotation axis a, is formed in a cylindrical shape, and is located surrounding the fixed shaft 10. The first heat transfer component 21 has a first heat transfer component main body 21a and convex portions 21b and 22c. The first heat transfer component main body 21a has a uniform inner diameter and outer diameter over the entire circumference.

The convex portions 21b and 21c are formed at both ends of the first heat transfer component body 21a so as to extend in a direction away from the rotation axis a. The protrusions 21b and 21c have an annular shape. The convex portions 21b and 21c do not need to be continuously and integrally formed with the first heat transfer component body 21a, and may be fixed to the outer circumferential surface of the first heat transfer component body 21a by, for example, welding or screws.

The coefficient of thermal expansion of the first heat transfer component 21 is larger than the coefficient of thermal expansion of the second heat transfer component 22. The material of the first heat transfer component 21 is, for example, Mo or TZM (titanium zirconium molybdenum alloy). Note that the thermal expansion coefficient of Mo is 5.1×10 ⁻⁶ to 5.7×10 ⁻⁶ /K, and the thermal expansion coefficient of TZM is 5.3×10 ⁻⁶ /K.

The second heat transfer component 22 extends along the rotation axis a, is formed in a cylindrical shape, and is in contact with the inner surface of the first heat transfer component 21 (first heat transfer component main body 21a). The second heat transfer component 22 is attached to the first heat transfer component 21 by interference fit, for example. The second heat transfer component 22 is located between the fixed shaft 10 and the first heat transfer component 21. In one example, the second heat transfer component 22 has a uniform inner diameter and outer diameter over the entire circumference, and includes a radial bearing surface S22 on the inner peripheral surface.

The material of the second heat transfer component 22 is a medium-grain cemented carbide, a coarse-grained cemented carbide, an ultrafine-grained alloy, an iron-nickel alloy, or the like. As the medium grain cemented carbide, for example, VD15 manufactured by Fuji Dice Co., Ltd. can be used. As the coarse grain cemented carbide, for example, C50 manufactured by Fuji Dice Co., Ltd. can be used. The ultrafine grain alloy may be, for example, VF-10 in the CIS (Cemented Carbide Tools Association) standard 019D. For example, Invar can be used as the iron-nickel alloy. Here, the average particle size of the particles constituting the medium grain cemented carbide is from 1.0 μm to 2.5 μm. Note that the above average particle size refers to the average particle size of tungsten carbide (WC) based on JIS (Japanese Industrial Standard) B 4054:2020. Further, the above-mentioned average particle size in the alloy refers to the average particle size of all particles. The average grain size of the particles constituting the coarse-grained cemented carbide is from 2.5 μm to 5.0 μm. The average particle size of the particles constituting the ultrafine particle alloy is less than 1.0. Note that the above average particle size is the average particle size before manufacturing of the rotating anode X-ray tube 1 is started, and is calculated by a calculation method based on JIS B 4054:2020.

The thermal expansion coefficient of the medium grain cemented carbide (VD15 manufactured by Fuji Dice Co., Ltd.) is 4.7×10 ⁻⁶ /K. The thermal expansion coefficient of the coarse grained cemented carbide (C50 manufactured by Fuji Dice Co., Ltd.) is 4.8×10 ⁻⁶ /K. The thermal expansion coefficient of the ultrafine particle alloy (VF-10) is 4.9×10 ⁻⁶ /K. The thermal expansion coefficient of iron-nickel alloy (Invar) is 1.2×10 ⁻⁶ to 2.0×10 ⁻⁶ /K.

The first stopper 23 has an annular shape and is fixed to one end of the first heat transfer component 21 . The first stopper 23 faces one end surface 22a of the second heat transfer component 22. In one example, the first stopper 23 is in contact with one end surface 22a of the second heat transfer component 22.

The first stopper 23 is made of metal such as Fe alloy or Mo alloy. In one example, the first stopper 23 includes a thrust bearing surface S23 that faces the thrust bearing surface S11i of the fixed shaft 10 in the direction along the rotation axis a. The thrust bearing surface S23 is located on the inner peripheral side of the first stopper 23 and has an annular shape.

The gap between the first stopper 23 and the fixed shaft 10 (first small diameter portion 12) is set to a value that can maintain rotation of the rotating body 20 and suppress leakage of the liquid metal LM. From the above, the gap is small, and the first stopper 23 functions as a labyrinth seal ring.

The second stopper 24 has an annular shape and is fixed to the other end of the first heat transfer component 21 . The second stopper 24 faces the other end surface 22b of the second heat transfer component 22. In one example, the second stopper 24 is in contact with the other end surface 22b of the second heat transfer component 22.

The second stopper 24 is made of metal such as Fe alloy or Mo alloy. In one example, the second stopper 24 includes a thrust bearing surface S24 that faces the thrust bearing surface S11j of the fixed shaft 10 in the direction along the rotation axis a. The thrust bearing surface S24 is located on the inner peripheral side of the second stopper 24 and has an annular shape.

The gap between the second stopper 24 and the fixed shaft 10 (second small diameter portion 13) is set to a value that can maintain rotation of the rotating body 20 and suppress leakage of the liquid metal LM. From the above, the gap is small, and the second stopper 24 functions as a labyrinth seal ring.
The first stopper 23 and the second stopper 24 limit movement of the second heat transfer component 22 in the direction along the rotation axis a.

The cylindrical portion 25 is joined to the outer peripheral surface of the convex portion 21b of the first heat transfer component 21. The cylindrical portion 25 is made of metal such as copper (Cu) or a copper alloy.

The liquid metal LM is filled in a gap between the fixed shaft 10 (large diameter portion 11), the second heat transfer component 22, the first stopper 23, and the second stopper 24. The liquid metal LM can be made of a material such as a GaIn (gallium-indium) alloy or a GaInSn (gallium-indium-tin) alloy. During the rotational operation of the rotating body 20, the liquid level of the liquid metal LM on the rotation axis a side is located closer to the rotation axis a than the radial bearing surfaces S11a and S11b. Thereby, depletion of the liquid metal LM in the bearing gap can be suppressed. The liquid metal LM forms a hydrodynamic sliding bearing together with the bearing surface of the fixed shaft 10 and the bearing surface of the rotating body 20.

The anode target 50 is formed in an annular shape and is provided coaxially with the fixed shaft 10 , the first heat transfer component 21 , and the second heat transfer component 22 . The anode target 50 includes an anode target body 51 and a target layer 52 provided on a part of the outer surface of the anode target body 51. The anode target body 51 is formed in an annular shape. The anode target body 51 surrounds the outer periphery of the first heat transfer component 21 and is fixed to the first heat transfer component 21 .

The anode target body 51 is made of molybdenum, tungsten, or an alloy thereof. The melting point of the metal forming the target layer 52 is the same as or higher than the melting point of the metal forming the anode target body 51. For example, the anode target body 51 is made of a molybdenum alloy, and the target layer 52 is made of a tungsten alloy.

The anode target 50 is rotatable together with the rotating body 20. When electrons collide with the target surface S52 of the target layer 52, a focal point is formed on the target surface S52. Thereby, the anode target 50 emits X-rays from the focal point.

The cathode 60 is spaced apart from the target layer 52 of the anode target 50 and is disposed opposite to the target layer 52 . Cathode 60 is attached to the inner wall of vacuum envelope 70 . The cathode 60 has a filament 61 as an electron emission source that emits electrons to irradiate the target layer 52.

The vacuum envelope 70 is formed into a cylindrical shape. The vacuum envelope 70 is made of glass, ceramic, and metal. In the vacuum envelope 70, the outer diameter of the portion facing the anode target 50 is larger than the outer diameter of the portion facing the cylindrical portion 25. The vacuum envelope 70 has openings 71 and 72. The vacuum envelope 70 is sealed, houses the anode target 50 and the cathode 60, and fixes the fixed shaft 10. The inside of the vacuum envelope 70 is maintained in a vacuum state (reduced pressure state).

In order to maintain the airtight state of the vacuum envelope 70, the opening 71 is hermetically joined to one end of the fixed shaft 10 (the first small diameter part 12), and the opening 72 is joined to the other end of the fixed shaft 10 (the first small diameter part 12). 2) and is hermetically joined to the small diameter portion 13). The vacuum envelope 70 fixes the first small diameter portion 12 and the second small diameter portion 13 of the fixed shaft 10. In other words, the first small-diameter portion 12 and the second small-diameter portion 13 function as supporting portions on both sides of the bearing.

The rotating anode type X-ray tube 1 includes a cooling pipe 40 that takes the cooling liquid L into the inside of the fixed shaft 10 and discharges the cooling liquid L from the inside of the fixed shaft 10. The cooling pipe 40 includes a first pipe section 41 and a second pipe section 42 . The annular portion 16 is liquid-tightly joined to the second bottom surface 10b2 of the fixed shaft 10. The first tube portion 41 has an outer peripheral surface liquid-tightly joined to the opening of the annular portion 16 and extends to the outside of the fixed shaft 10 . The first pipe portion 41 has an intake port 41 a for introducing the coolant L into the fixed shaft 10 .

The annular portion 17 is liquid-tightly joined to the first bottom surface 10b1 of the fixed shaft 10. The second tube portion 42 has an outer peripheral surface liquid-tightly joined to the opening of the annular portion 17 and extends to the outside of the fixed shaft 10 . The second pipe portion 42 has a discharge port 42a for discharging the coolant L to the outside of the fixed shaft 10.

The fixed shaft 10 forms a flow path for the cooling liquid L together with the cooling pipe 40. The coolant L is taken into the fixed shaft 10 through the intake port 41 a of the first pipe section 41 , passes through the inside of the fixed shaft 10 , and flows to the outside of the fixed shaft 10 from the discharge port 42 a of the second pipe section 42 . is discharged. Note that the cooling liquid L may flow in the opposite direction. In this case, the first pipe section 41 has a discharge port, and the second pipe section 42 has an intake port.
Note that when the heat inside the fixed shaft 10 is released by cooling the first bottom surface 10b1 and the second bottom surface 10b2 with a heat exchanger, a rotating anode type is used without the cooling pipe 40, the annular portion 16, and the annular portion 17. The X-ray tube 1 may also be configured.

The stator coil 2 is provided so as to surround the outside of the vacuum envelope 70 so as to face the outer circumferential surface of the rotating body 20 , more specifically, the outer circumferential surface of the cylindrical portion 25 . The stator coil 2 has an annular shape. The stator coil 2 generates a magnetic field applied to the cylindrical portion 25 (the rotating body 20) to rotate the rotating body 20 and the anode target 50.
As described above, an X-ray tube device including the rotating anode type X-ray tube 1 is formed.

In the operating state of the X-ray tube device, the stator coil 2 generates a magnetic field applied to the rotating body 20 (particularly the cylindrical portion 25), so the second heat transfer component 22 rotates. As a result, the first heat transfer component 21 and the anode target 50 also rotate together. Further, a current is applied to the cathode 60 and a negative voltage is applied, and a relatively positive voltage is applied to the anode target 50.

This creates a potential difference between the cathode 60 and the anode target 50. Filament 61 emits electrons. This electron is accelerated and collides with the target surface S52. As a result, a focal point is formed on the target surface S52, and the focal point emits X-rays when it collides with electrons. Electrons (thermoelectrons) that collide with the anode target 50 are converted into X-rays, and the rest are converted into thermal energy. Note that the electron emission source of the cathode 60 is not limited to a filament, and may be a flat emitter, for example.

The heat generated in the anode target 50 is transmitted from the target surface S52 to the inside of the target layer 52, the anode target body 51, the first heat transfer component 21, the second heat transfer component 22, the liquid metal LM, and the fixed shaft 10 in this order. The heat transferred to the fixed shaft 10 is transferred from the heat transfer portion 10a of the fixed shaft 10 to the coolant L, and is released to the outside of the slide bearing 3 together with the coolant L.

FIG. 3 is an enlarged sectional view showing a part of the rotating anode X-ray tube 1 according to the above embodiment, and is a diagram showing a state from when heat is input to the anode target 50 until the anode target 50 is cooled. be.

As shown in FIG. 3, when heat is generated in the anode target 50, the first heat transfer component 21 thermally expands. Then, since the thermal expansion coefficient of the first heat transfer component 21 is larger than that of the second heat transfer component 22, an annular gap S is formed between the first heat transfer component 21 and the second heat transfer component. be done. The gap S functions as a heat insulator that blocks heat exchange between the first heat transfer component 21 and the second heat transfer component 22. That is, the heat transmitted from the anode target 50 to the first heat transfer component 21 is suppressed from being transmitted to the second heat transfer component 22.

On the other hand, when heat is generated in the anode target 50, the outer peripheral surface of the first heat transfer component main body 21a also expands in a direction away from the rotation axis a. At this time, the cylindrical portion 25 does not contact the outer peripheral surface of the first heat transfer component main body 21a because it is attached to the convex portion 21b.

When the temperature of the anode target 50 decreases, the gap S formed by the thermal expansion of the first heat transfer component 21 becomes smaller, and heat conduction from the first heat transfer component 21 to the second heat transfer component 22 is promoted. .

The effects of the rotating anode X-ray tube 1 according to the above embodiment will be explained below.
According to the rotating anode X-ray tube 1 configured as described above, the rotating anode X-ray tube 1 includes a cathode 60, an anode target 50, a sliding bearing 3 having a fixed shaft 10, and a rotating body 20. , and a vacuum envelope 70. The fixed shaft 10 has a heat radiating section that radiates heat. The rotating body 20 includes a first heat transfer component 21 and a second heat transfer component 22 that contacts the inner surface of the first heat transfer component 21 . The coefficient of thermal expansion of the first heat transfer component 21 is larger than the coefficient of thermal expansion of the second heat transfer component 22. As a result, it is possible to obtain a rotating anode type X-ray tube that can make maximum use of conduction cooling when the temperature of the sliding bearing is within an allowable range.

The rotating body 20 is fixed to the first heat transfer component 21 and has a first stopper 23 facing one end surface 22a of the second heat transfer component 22, and a first stopper 23 that is fixed to the first heat transfer component 21 and has a second heat transfer component. It has a second stopper 24 facing the other end surface 22b of the component 22. Thereby, the second heat transfer component 22 can be prevented from moving in the direction along the rotation axis a with respect to the first heat transfer component 21.

The rotating anode type X-ray tube 1 includes a cooling pipe 40 having an intake port 41a for introducing the coolant into the inside of the fixed shaft 10, and a discharge port 42a for discharging the coolant to the outside of the fixed shaft 10. The heat radiation section is a heat transfer section 10a that transfers heat to the refrigerant. Thereby, it becomes possible to flow the coolant by natural convection due to heat inside the fixed shaft 10, and the cost for cooling the fixed shaft 10 can be suppressed.

(Modified example)
Next, a modification of the rotating anode X-ray tube 1 according to the above embodiment will be described. The rotating anode X-ray tube 1 has the same structure as the above embodiment except for the structure described in this modification. FIG. 4 is an enlarged sectional view showing a part of a modification of the rotating anode X-ray tube according to the above embodiment.

As shown in FIG. 4, the second heat transfer component 22 is joined to the first heat transfer component 21 at joints 26 and 27 outside the region A facing the anode target 50. As shown in FIG. The joint parts 26 and 27 can be, for example, welded parts or brazed parts. The joint portion 26 and the joint portion 27 may extend over the entire circumference of the second heat transfer component 22 and the first heat transfer component 21, or may extend between the second heat transfer component 22 and the first heat transfer component 21. It does not have to extend all the way around. If the joints 26 and 27 do not extend all the way around the first heat transfer component 21 and the second heat transfer component 22, they can be formed by spot welding, for example.

Although not shown, the first heat transfer component 21 and the second heat transfer component 22 may be removably fixed using screws. The first heat transfer component 21 and the second heat transfer component 22 may be fixed at one location, for example, may be fixed only at the joint portion 26.

In the above embodiment, it has been described that the movement of the second heat transfer component 22 in the direction along the rotation axis a is limited by the first stopper 23 and the second stopper 24, but in this modification, the second heat transfer component 22 is Since it is fixed to the first heat transfer component 21, it is not necessary to restrict the movement of the second heat transfer component 22 by the first stopper 23 and the second stopper 24.

That is, in this modification, the first stopper 23 and the second stopper 24 can be annular parts that act as labyrinth seal rings to suppress leakage of the liquid metal LM and constitute a dynamic pressure type thrust sliding bearing together with the fixed shaft 10. can. When the first stopper 23 is the first annular component and the second stopper 24 is the second annular component, the first annular component and the second annular component may be fixed to the first heat transfer component 21, or may be fixed to the second heat transfer component 21. It may be fixed to the thermal component 22. The first annular component may be located at one end surface 22a of the second heat transfer component 22 with a gap provided therebetween. The second annular component may be located at the other end surface 22b of the second heat transfer component 22 with a gap provided therebetween.

According to the modified example of the rotary anode type X-ray tube 1 according to the above embodiment configured as described above, it is possible to obtain the same effects as the rotary anode type X-ray tube according to the above embodiment.

Although embodiments of the present invention have been described, the above embodiments are presented as examples and are not intended to limit the scope of the invention. The novel embodiment described above can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. The above-described embodiments and modifications thereof are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

DESCRIPTION OF SYMBOLS 1... Rotating anode type X-ray tube, 3... Sliding bearing, 10... Fixed shaft, 10a... Heat transfer part, 10b1... First bottom surface, 10b2... Second bottom surface, 16, 17... Annular part, 20... Rotating body, 21...First heat transfer component, 22...Second heat transfer component, 22a...One end surface, 22b...Other end surface, 23...First stopper, 24...Second stopper, 25...Cylinder part, 26...Joint part, 40... Cooling pipe, 41...First tube section, 41a...Intake port, 42...Second tube section, 42a...Discharge port, 50...Anode target, 51...Anode target body, 52...Target layer, 60...Cathode, 61... Filament, 70... Vacuum envelope, A... Region, L... Coolant, LM... Liquid metal, S... Gap, a... Rotation axis.

Claims (5)

a cathode that emits electrons;
an anode target that receives the electrons and generates X-rays;
a rotating body connected to the anode target and extending along a rotational axis; a fixed shaft rotatably supporting the rotating body; a lubricant held between the rotating body and the fixed shaft; a plain bearing having a
a vacuum envelope that houses the cathode and the anode target and fixes the fixed shaft;
The fixed shaft has a heat radiation part that releases internal heat to the outside,
The rotating body is
a first heat transfer component extending along the rotational axis and positioned around the fixed shaft;
a second heat transfer component extending along the rotational axis and in contact with an inner surface of the first heat transfer component;
The anode target surrounds the outer peripheral surface of the first heat transfer component and is fixed to the first heat transfer component,
The coefficient of thermal expansion of the first heat transfer component is greater than the coefficient of thermal expansion of the second heat transfer component.
Rotating anode type X-ray tube. The material of the first heat transfer component is molybdenum or titanium zirconium molybdenum alloy,
The material of the second heat transfer component is a medium-grained cemented carbide, a coarse-grained cemented carbide, an ultrafine-grained alloy, or an iron-nickel alloy.
The rotating anode X-ray tube according to claim 1. The rotating body is
a first stopper fixed to the first heat transfer component and facing one end surface of the second heat transfer component in a direction along the rotation axis;
a second stopper fixed to the first heat transfer component and facing the other end surface of the second heat transfer component in the direction along the rotation axis;
The first stopper and the second stopper limit movement of the second heat transfer component in a direction along the rotation axis.
The rotating anode X-ray tube according to claim 1 or 2. the second heat transfer component is fixed to the first heat transfer component outside a region surrounded by the anode target;
The rotating anode X-ray tube according to claim 1 or 2. Further comprising a cooling pipe having an intake port for introducing the refrigerant into the inside of the fixed shaft, and a discharge port for discharging the refrigerant to the outside of the fixed shaft,
The heat radiation section is a heat transfer section that transfers heat to the refrigerant.
The rotating anode X-ray tube according to claim 1 or 2.

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