WO2024014179A1

WO2024014179A1 - Rotating anode x-ray tube

Info

Publication number: WO2024014179A1
Application number: PCT/JP2023/020757
Authority: WO
Inventors: 広之熊抱
Original assignee: キヤノン電子管デバイス株式会社
Priority date: 2022-07-11
Filing date: 2023-06-05
Publication date: 2024-01-18

Abstract

This rotating anode X-ray tube comprises a vacuum envelope, and a cathode and a rotating anode structure accommodated in the vacuum envelope. The rotating anode structure includes a fixed shaft, a rotating shaft provided on the outer peripheral side of the fixed shaft, and a target that rotates together with the rotating shaft and generates X-rays by receiving an electron beam emitted from the cathode. A bearing gap filled with a liquid lubricant is provided between the fixed shaft and the rotating shaft. Magnetic fine particles with magnetism are dispersed in the liquid lubricant, and a magnetic field is provided in the bearing gap.

Description

rotating anode x-ray tube

Embodiments of the present invention relate to a rotating anode X-ray tube.

A rotating anode X-ray tube has a fixed shaft and a rotating shaft in a vacuum inside a vacuum envelope.The anode is fixed to the rotating shaft, and the rotating shaft is rotated with respect to the fixed shaft by a stator coil. It disperses the heat generated by the The gap between the rotating shaft and the fixed shaft (bearing gap) is filled with liquid metal, and this liquid metal becomes a lubricant for the hydrodynamic sliding bearing when the rotating anode rotates. The rotating anode is supported by the dynamic pressure effect generated in this dynamic pressure slide bearing.

Japanese Patent Application Publication No. 8-212949

Rotating anode X-ray tubes that use liquid metal as a lubricant are thought to be held in place by the surface tension of their bearings, but liquid metal (hereinafter referred to as "liquid lubricant") ) could leak out from the bearing gap.
If the liquid lubricant leaks, the dynamic pressure effect decreases or disappears, causing direct contact between the rotating shaft and the fixed shaft, causing rotation to stop, and the liquid lubricant causing a potential difference inside the X-ray tube. There is an inconvenience that discharge occurs when it goes to a certain part.

Embodiments of the present invention provide a rotating anode X-ray tube that can prevent liquid lubricant from leaking from a bearing gap.

One embodiment includes a cathode and a rotating anode assembly housed in the vacuum envelope, and the rotating anode assembly includes a fixed shaft, a rotating shaft provided on the outer circumferential side of the fixed shaft, and the rotating anode assembly. a target that rotates together with the shaft and generates X-rays upon receiving the electron beam irradiated from the cathode, and a bearing filled with a liquid lubricant between the fixed shaft and the rotating shaft; The rotary anode X-ray tube is provided with a gap, magnetic fine particles having magnetism are dispersed in the liquid lubricant, and a magnetic field is applied to the bearing gap.

FIG. 1 is a sectional view of a rotating anode X-ray tube according to a first embodiment. FIG. 2 is a plan view of a magnet provided on the rotating shaft side in the rotating anode X-ray tube shown in FIG. FIG. 3 is a sectional view of a rotating anode X-ray tube according to a second embodiment, showing the arrangement of magnets with respect to the bearing gap. FIG. 4 is a sectional view of a rotating anode X-ray tube according to a third embodiment. FIG. 5 is a sectional view showing an end of a bearing gap in a rotating anode X-ray tube according to a fourth embodiment. FIG. 6 is a sectional view of a rotating anode X-ray tube according to a fifth embodiment. FIG. 7 is a sectional view of a rotating anode X-ray tube according to a sixth embodiment. FIG. 8 is a sectional view of a rotating anode X-ray tube according to a seventh embodiment. FIG. 9 is a sectional view of a rotating anode X-ray tube according to the eighth embodiment. FIG. 10 is a sectional view of a rotating anode X-ray tube according to a ninth embodiment. FIG. 11 is a sectional view of a rotating anode X-ray tube according to a tenth embodiment. FIG. 12 is a sectional view of a rotating anode X-ray tube according to the eleventh embodiment. FIG. 13 is a sectional view of a rotating anode X-ray tube according to the twelfth embodiment. FIG. 14 is a sectional view showing a modification of the first embodiment. FIG. 15 is a sectional view showing the arrangement of magnets according to a modification of the rotating anode X-ray tube according to the sixth embodiment.

Below, a rotating anode X-ray tube and a method for manufacturing the rotating anode X-ray tube according to one embodiment will be described in detail with reference to the drawings. In addition, in order to make the explanation more clear, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect, but this is just an example, and the drawings do not reflect the present invention. It does not limit interpretation. In addition, in this specification and each figure, the same reference numerals are given to components that perform the same or similar functions as those described above with respect to the existing figures, and overlapping detailed explanations may be omitted as appropriate. .

(First embodiment)
First, a first embodiment will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, the rotating anode X-ray tube 1 according to the first embodiment includes a vacuum envelope 3, and a rotating anode assembly 5 and a cathode 7 housed in the vacuum envelope 3. . A stator coil 9 is provided outside the vacuum envelope 3.

The rotating anode structure 5 includes a target 13, a fixed shaft 15, a rotating shaft 17, and a sliding bearing 19 formed between the fixed shaft 15 and the rotating shaft 17.
The target 13 is formed into a disk shape and is fixed to the outer peripheral surface of the rotating shaft 17. The target 13 is provided coaxially with the fixed shaft 15 and the rotating shaft 17.
The target 13 includes a target body 13a and a target layer 13b provided on a part of the outer surface of the target body 13a. The target 13 is rotatable together with the rotating shaft 17, and emits X-rays when electrons are incident on the target layer 13b.

The fixed shaft 15 is formed in a cylindrical shape and includes one end side portion 15a located on one end side of the tube axis a, and the other end side portion 15b located on the other end side in the tube axis direction. The one end side portion 15a and the other end side portion 15b are each fixed to the vacuum envelope 3 via fixing members (not shown).
The fixed shaft 15 has a refrigerant passage 16 provided therein, and heat is radiated through the cooling medium introduced into the refrigerant passage 16.
The fixed shaft 15 rotatably supports a rotating shaft 17 provided on its outer periphery.
The fixed shaft 15 is made of metal such as Fe (iron) alloy or Mo (molybdenum) alloy.

The rotating shaft 17 is arranged coaxially with the fixed shaft 15 on the outer periphery of the fixed shaft 15. The rotating shaft 17 includes a cylindrical main body 17a, an annular one end side cover part 17b provided on one end side of the main body 17a, and an annular other end side cover part 17c provided on the other end side. . The rotating shaft 17 is made of metal such as Fe alloy or Mo alloy.
A drive rotor 31 is provided at a position facing the stator coil 9 on the outer peripheral surface of the main body 17a. The drive rotor 31 has a cylindrical shape and is fixed to the outer peripheral surface of the main body 17a. The drive rotor 31 is made of, for example, Cu (copper).

The sliding bearing 19 includes a bearing gap 21 and a liquid lubricant LM filled in the bearing gap 21.
The gap size of the bearing gap 21 is such that one end 21a and the other end 21b of the fixed shaft 15 in the longitudinal direction are narrower than the intermediate portion 21c.

Magnetic fine particles having magnetism are dispersed in the liquid lubricant LM. The magnetic fine particles are formed, for example, by coating iron oxide particles with aluminum or silica.

In this embodiment, a magnetic field is applied to one end 21a and the other end 21b of the bearing gap 21, respectively.
The magnetic field is applied by

permanent magnets

23a and 23b placed at one end 21a and the other end 21b, respectively.
One permanent magnet 23a is provided on the outer periphery of the one end side lid portion 17b, and the other permanent magnet 23b is provided inside the one end side portion 15a of the fixed shaft 15. The other permanent magnet 23b may be embedded in one end side portion 15a of the fixed shaft 15.

As shown in FIG. 2, one of the permanent magnets 23a has an annular shape, with an N pole on the inner circumferential side and an S pole on the outer circumferential side. The other permanent magnet 23b has an annular shape like the one permanent magnet 23a, but since it is arranged on the inner circumferential side of the one permanent magnet 23a, it has a smaller size than the one permanent magnet 23a. It is circular.
The inner circumferential side of one permanent magnet 23a is a north pole, and the outer circumferential side of the other permanent magnet 23b, which faces the inner circumferential side of one permanent magnet 23a across the bearing gap 21, is an south pole.

As shown in FIG. 1, the cathode 7 is arranged to face the target layer 13b of the target 13 at a distance. The cathode 7 is attached to the inner wall of the vacuum envelope 3. The cathode 7 has a filament 7a as an electron emission source that emits electrons to irradiate the target layer 13b.

The vacuum envelope 3 is formed into a cylindrical shape. The vacuum envelope 3 is made of glass and metal.

Next, the effects of the rotating anode X-ray tube according to the first embodiment will be explained.
As shown in FIG. 1, in the operating state of the rotating anode X-ray tube 1, the stator coil 9 generates a magnetic field applied to the rotating shaft 17 (particularly the drive rotor 31), and the rotating shaft 17 rotates around the fixed shaft 15. . This causes the target 13 to rotate. Further, a relatively negative voltage is applied to the cathode 7, and a relatively positive voltage is applied to the target 13.
This creates a potential difference between the cathode 7 and the target 13. Therefore, when the filament 7a emits electrons, the electrons are accelerated and collide with the target layer 13b. Thereby, the target layer 13b emits X-rays when collided with electrons, and the emitted X-rays are transmitted through the vacuum envelope 3 and emitted.
During X-ray radiation, high heat is generated in the target 13 due to electron impact.

The heat generated in the target 13 due to the electron impact is conducted to the fixed shaft 15 via the liquid lubricant LM of the sliding bearing 19, and the heat is released from the fixed shaft 15 to the cooling refrigerant in the refrigerant passage 16 for cooling.
On the other hand, in the bearing gap 21 of the sliding bearing 19, the gap size is narrowed between one end 21a and the other end 21b, and a magnetic field is applied by

permanent magnets

23a and 23b.
In this way, by applying a magnetic field to the bearing gap 21, in the liquid lubricant LM filled in each

end

21a, 21b of the bearing gap 21, the dispersed magnetic fine particles (not shown) are applied to the magnetic field ( Since the liquid lubricant LM is attracted by the action of magnetic lines of force and remains within the bearing gap between the

ends

21a and 21b, it acts as a dam and holds the liquid lubricant LM within the gap, thereby preventing leakage of the liquid lubricant.
Since one permanent magnet 23a is arranged outside the rotating shaft 17, it can be installed more easily than when it is embedded in the rotating shaft 17.
Both the one permanent magnet 23a and the other permanent magnet 23b are annular magnets with magnetic poles formed on the inner circumferential side and the outer circumferential side, so that the structure can be simplified.

Other embodiments will be described below, but in the following description, parts that have the same functions and effects as those of the first embodiment described above will be given the same reference numerals, and detailed explanations of those parts will be omitted. .

(Second embodiment)
FIG. 3 shows a second embodiment. In the second embodiment, rod-shaped

permanent magnets

24a and 24b are used in place of the annular

permanent magnets

23a and 23b of the first embodiment. FIG. 3 shows a cross section of one end 21a (see FIG. 1) of the bearing gap 21, and one rod-shaped permanent magnet 24a and the other permanent magnet 24b are located on the inner and outer sides of the bearing gap 21. One rod-shaped permanent magnet 24a and the other permanent magnet 24b are arranged in a circular shape. One rod-shaped permanent magnet 24a and the other permanent magnet 24b are arranged such that opposite magnetic poles face each other on the inner circumferential side and the outer circumferential side.
Further, the second embodiment differs from the first embodiment in that one of the permanent magnets 24a on the outer peripheral side is embedded in the one end side cover 17b of the rotating shaft 17.
Although the other end 21b of the bearing gap 21 is not shown in the second embodiment, one permanent magnet 24a may be arranged on the outer periphery of the rotating shaft 17 as in the first embodiment. , may be embedded in the rotating shaft 17 similarly to the one end portion 21a.

As shown in FIG. 3, in this second embodiment, the lines of magnetic force K acting on the magnets have a spread, so the one and the other

permanent magnets

24a and 24b facing each other in the circumferential direction are spaced apart in the circumferential direction. Even in the case where the bearing gap 21 is arranged in the same manner as shown in FIG.
In the second embodiment shown in FIG. 3, the one and the other

permanent magnets

24a and 24b facing each other in the circumferential direction are arranged at an interval of about 45 degrees in the circumferential direction, but the interval is not limited to 30 degrees or 15 degrees. They may be arranged at arbitrary intervals such as 60 degrees or 60 degrees.
In this second embodiment, since highly versatile bar magnets are used for the one and the other

permanent magnets

24a and 24b, manufacturing is easy. Further, by changing the arrangement density of one and the other

permanent magnets

24a and 24b in the circumferential direction, the magnetic force acting on the bearing gap 21 can be easily adjusted.

(Third embodiment)
A third embodiment will be described with reference to FIG. 4.
In this third embodiment, one annular permanent magnet 23a (see FIG. 2) and the other annular permanent magnet 23b are arranged side by side on the fixed shaft 15 side at one end 21a and the other end 21b of the bearing gap 21. ing.
Further, a trap 26 is formed at one end 21a and the other end 21b of the bearing gap 21 to form irregularities to facilitate holding the liquid lubricant LM.
One permanent magnet 23a and the other permanent magnet 23a have the same size and shape, but have different magnetic poles on the inner circumferential side and the outer circumferential side. That is, one permanent magnet 23a has an N pole on the outer circumference side and an S pole on the inner circumference side, and the other permanent magnet 23b has an N pole on the outer circumference side and an S pole on the inner circumference side.

According to the third embodiment, the same effects as those of the first embodiment can be achieved, and manufacturing is easy because both the one and the other

permanent magnets

23a and 23b can be provided on the fixed shaft 15. .
Furthermore, since the traps 26 are provided at the one end 21a and the other end 21 of the bearing gap 21, the liquid lubricant LM can be easily held in synergy with the action of the magnetic force.

(Fourth embodiment)
A fourth embodiment will be described with reference to FIG. 5.
In the fourth embodiment, one annular permanent magnet 23 (see FIG. 2) is arranged at one end 21a and the other end 21b of the bearing gap 21 on the fixed shaft 15 side. This permanent magnet 23 has an annular N pole on one side and an S pole on the other side.
According to the fourth embodiment, the same effects as the third embodiment are achieved, and since only one permanent magnet is required at each end 21a and the other end 21b of the bearing gap 21, the structure is further improved. can be easily done.

(Fifth embodiment)
A fifth embodiment will be described with reference to FIG. 6.
In this fifth embodiment, while the third embodiment has one annular permanent magnet 23 arranged on the fixed shaft 15 side, two annular

permanent magnets

23a and 23b are arranged on the rotating shaft 17 side. Being there is different.
Further, in the fifth embodiment, on the other end 21b side of the bearing gap 21, one permanent magnet 23a and the other permanent magnet 23b are arranged on the outer circumferential side of the rotating shaft 17, and one end of the bearing gap 21 On the part 21a side, one permanent magnet 23a and the other permanent magnet 23b are embedded in the one end side cover part 17b of the rotating shaft 17.

According to the fifth embodiment, the same effects as the third embodiment can be achieved.
Furthermore, on the other end 21b side of the bearing gap 21, one permanent magnet 23a and the other permanent magnet 23b are arranged on the outer circumferential side of the rotating shaft 17, so there is no need to embed them in the rotating shaft 17. Easy to install.

(Sixth embodiment)
As shown in FIG. 7, in the sixth embodiment, a magnetic field is applied to an intermediate portion 21c of the bearing gap 21, excluding the one end portion 21a and the other end portion 21b.
The magnetic field is applied by a plurality of permanent magnets 23 arranged along the longitudinal direction of the intermediate portion 21c.
As shown in FIG. 2, each permanent magnet 23 has a ring shape, and the inner circumferential side is magnetized to an S pole or N pole, and the outer circumferential side is magnetized to a magnetic pole opposite to the inner circumferential side. ing. That is, in Fig. 2, the inner circumferential side is the north pole and the outer circumferential side is the south pole, but on the contrary, two types of poles are used, in which the inner circumferential side is the south pole and the outer circumferential side is the north pole. .
As shown in FIG. 7, in the arrangement direction of each permanent magnet 23, adjacent magnets have N poles and S poles arranged alternately. Each permanent magnet 23 is embedded in the fixed shaft 15.

Next, the effects of the rotating anode X-ray tube according to the sixth embodiment will be explained.
In the sixth embodiment, by applying a magnetic field to the intermediate portion 21c of the bearing gap 21, the dispersed magnetic fine particles (not shown) in the liquid lubricant LM filled in the bearing gap 21 are exposed to the magnetic field ( The liquid lubricant LM is attracted by the magnetic field lines K) and remains in the intermediate portion 21c of the bearing gap 21, so that the liquid lubricant LM is held within the gap.
That is, the liquid lubricant LM in which magnetic fine particles are dispersed is held in the pressure generating portion of the slide bearing 19 to prevent contact between the rotating shaft 17 and the fixed shaft 15 due to depletion of the liquid lubricant LM. Further, even when the rotating shaft 17 is stopped, by holding the liquid lubricant LM on the bearing surface of the sliding bearing 19, contact between the rotating shaft 17 and the fixed shaft 15 can be prevented.

The permanent magnet 23 is an annular magnet with magnetic poles formed on the inner circumferential side and the outer circumferential side, so that it can have a simple structure.
As shown in FIG. 7, in this embodiment, the adjacent permanent magnets 23 have different opposing magnetic poles, so a stronger magnetic field is applied to the slide bearing 19 than when the opposing magnetic poles are the same. can be applied.

(Seventh embodiment)
FIG. 8 shows a seventh embodiment. In the seventh embodiment, a groove 25 is formed in the bearing gap 21 in the sliding bearing 19, and the magnet 23 is provided only at a position corresponding to the groove 25.
In FIG. 8, only one groove 25 is shown, but in reality, a plurality of grooves 25 are formed at intervals along the direction of the tube axis a.

In the seventh embodiment, the groove 25 is formed between the bearing surface of the rotating shaft 17 by forming a step on the bearing surface of the fixed shaft 15, but the groove 25 is not limited to this. A step may be formed on the surface.
In this sliding bearing 19, by forming the groove 25, the liquid lubricant LM is held on the bearing surface by the pressure difference generated during rotation. Contact between the rotating shaft 17 and the fixed shaft 15 is prevented by installing the magnet 23 so that the lines of magnetic force K are arranged in the groove 25 that is the holding portion.
Similar to the sixth embodiment, the magnets 23 are ring-shaped magnets, and a plurality of magnets 23 are arranged side by side in the direction of the tube axis a, and adjacent magnets 23 have different magnetic poles facing each other.

According to the seventh embodiment, the liquid lubricant LM can be held in the groove 25 as in the sixth embodiment by the magnetic force line K passing through the groove 25, thereby preventing contact between the rotating shaft 17 and the fixed shaft 15. be able to.

(Eighth embodiment)
An eighth embodiment will be described with reference to FIG.
This eighth embodiment differs from the seventh embodiment shown in FIG. 8 in the form of the permanent magnet 23. That is, the permanent magnets 23 are arranged so that different magnetic poles face each other in the direction of the tube axis a.
In FIG. 9, two permanent magnets are arranged for one groove 25, but any number of permanent magnets, such as three or four, may be arranged in the tube axis direction. Note that each permanent magnet 23 is a ring-shaped magnet.

In the eighth embodiment, as in the seventh embodiment, the liquid lubricant LM can be held in the groove 25 by the magnetic force lines K passing through the groove 25, thereby preventing contact between the rotating shaft 17 and the fixed shaft 15. be able to.

(Ninth embodiment)
A ninth embodiment will be described with reference to FIG.
The ninth embodiment differs from the sixth embodiment in that a magnetic body 27 is provided on the rotating shaft 17 with respect to the rotating anode X-ray tube 1 according to the sixth embodiment.
The magnetic body 27 is made of iron, for example, and is provided facing the permanent magnet 23 provided on the fixed shaft 15 . The magnetic body 27 is ring-shaped like the permanent magnet 23.

According to the ninth embodiment, as extracted and shown in FIG. 10, it is possible to provide lines of magnetic force K that cross the bearing gap 21, and it is possible to apply a magnetic field to the liquid lubricant LM sealed in the bearing gap 21. . Thereby, the liquid lubricant LM can be held in the bearing gap 21, and contact between the rotating shaft 17 and the fixed shaft 15 can be prevented.

(10th embodiment)
A tenth embodiment will be described with reference to FIG. 11.
In this tenth embodiment, grooves 25 are formed in the sliding bearing 19 as in the seventh embodiment, and a permanent magnet 23 is arranged on the fixed shaft 15 at a position corresponding to the groove 25, and a magnetic material 27 is provided externally on the outer peripheral surface of the rotating shaft 17.
The magnetic body 27 is a ring-shaped iron material.

According to the tenth embodiment, the same effects as the seventh embodiment can be achieved.
Furthermore, by arranging the magnetic body 27 on the rotating shaft 17 so as to face the permanent magnet 23, the strength of the magnetic field can be increased. Thereby, the holding force for holding the liquid lubricant LM in the bearing gap 21 can be increased.
Moreover, since the magnetic body 27 is externally attached to the outer circumferential surface of the rotating shaft 17 and is not embedded, installation is easy and the configuration is simple.

(Eleventh embodiment)
An eleventh embodiment will be described with reference to FIG. 12.
In this 11th embodiment, a groove 25 is formed in the sliding bearing 19 similarly to the 8th embodiment, and a permanent magnet 23 is arranged at a position corresponding to the groove 25. Although the permanent magnet 23 was provided on the fixed shaft 15 in the eleventh embodiment, it is embedded in the rotating shaft 17 in this eleventh embodiment.

According to the eleventh embodiment, the same effects as the eighth embodiment can be achieved.
Note that the permanent magnet 23 may not be embedded in the rotating shaft 17, but may be externally fixed to the outer peripheral surface of the rotating shaft 17.

(12th embodiment)
A twelfth embodiment will be described with reference to FIG. 13.
In this twelfth embodiment, as in the ninth embodiment, ring-shaped permanent magnets 23 are provided on the fixed shaft 15 at intervals in the direction of the tube axis a, and a magnetic body 27 is provided on the rotating shaft 17. However, the permanent magnets 23 adjacent in the direction of the tube axis a have the same opposing magnetic poles. That is, each permanent magnet 23 has the same magnetic pole on the outer circumferential side. In this embodiment, the outer circumferential side is the north pole, and the inner circumferential side is the south pole.
According to the twelfth embodiment, the same effects as the ninth embodiment can be achieved.

The embodiment described above is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications 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.

For example, in the third to fifth embodiments, bar-shaped

permanent magnets

24a and 24b may be used instead of annular permanent magnets and arranged with an interval in the circumferential direction, as in the second embodiment.
In this case, in the third and fifth embodiments, a plurality of sets of permanent magnets with different magnetic poles facing each other are arranged at intervals in the circumferential direction, and in the fourth embodiment, one end of the fixed shaft 15 is arranged. Bar-shaped permanent magnets 24a having different magnetic poles at one end and the other end are arranged at intervals in the circumferential direction.

Also in the seventh to twelfth embodiments, instead of the annular permanent magnets 23, bar-shaped permanent magnets 23 may be arranged at intervals in the circumferential direction.

As shown in FIG. 14, in the first embodiment, one permanent magnet 23a is not limited to being provided on the outer peripheral side of the rotating shaft 17, but may be embedded in the rotating shaft 17. For example, in the modified example of FIG. Here, one of the permanent magnets 23a is embedded in the one end side lid portion 17b.

In the sixth embodiment and the seventh embodiment, each permanent magnet 23 is not limited to being provided on the fixed shaft 15, but each permanent magnet 23 may be embedded in the rotating shaft 17, or externally attached to the outer peripheral surface of the rotating shaft 17. It may be fixed by Furthermore, in the first embodiment and the second embodiment, the permanent magnet 23 may be placed on both the fixed shaft 15 and the rotating shaft 17.
In the ninth embodiment, the tenth embodiment, and the twelfth embodiment, permanent magnets 23 may be used instead of each magnetic body 27.

In the eleventh embodiment, the magnetic body 27 and the permanent magnets 23 may be provided on the fixed shaft 15 at positions corresponding to the respective permanent magnets 23 provided on the rotating shaft 17.

FIG. 15 shows a modification of the sixth embodiment. In FIG. 15, a cross section of the intermediate portion 21c of the bearing gap 21 is shown. In this modification, the permanent magnets 23 are not ring-shaped but bar magnets, and the bar magnets are arranged at intervals along the outer peripheral surface of the fixed shaft 15. Adjacent magnets 23 are arranged with opposing magnetic poles facing each other on the inner and outer circumferential sides.
The lines of magnetic force K act on adjacent magnets 23 so as to cross the bearing gap 21 .

Claims

comprising a vacuum envelope, and a cathode and rotating anode assembly housed within the vacuum envelope,
The rotating anode structure includes a fixed shaft, a rotating shaft provided on the outer circumferential side of the fixed shaft, and a target that rotates together with the rotating shaft and generates X-rays by receiving the electron beam irradiated from the cathode. , has
A bearing gap filled with a liquid lubricant is provided between the fixed shaft and the rotating shaft,
A rotating anode X-ray tube, wherein magnetic fine particles having magnetism are dispersed in the liquid lubricant and a magnetic field is applied to the bearing gap.
The rotating anode X-ray tube according to claim 1, wherein the magnetic field is applied to an end of the bearing gap.
The rotating anode X-ray tube according to claim 2, wherein the magnetic field is a magnetic flux that crosses the bearing gap by a magnet provided on at least one of the fixed shaft side and the rotating shaft side.
The rotating anode X-ray tube according to claim 3, wherein the magnets are a pair of permanent magnets provided with the bearing gap in between, and the magnets are provided with opposite magnetic poles facing each other.
4. The rotating anode X-ray tube according to claim 3, wherein the magnets are permanent magnets arranged side by side on the fixed shaft side or the rotating shaft side, with mutually opposite magnetic poles facing each other.
2. The rotating anode X-ray tube according to claim 1, wherein the bearing gap has a groove in which the gap is partially narrowed, and the magnetic field is applied to a region of the groove.
The rotating anode X-ray tube according to claim 6, wherein the magnetic field is formed by a magnetic flux that crosses the bearing gap by a magnet provided on at least one of the fixed shaft side and the rotating shaft side.
The rotating anode X-ray tube according to claim 6, wherein the magnetic field is formed by a magnet provided on at least one of the fixed shaft side and the rotating shaft side, and a magnetic material provided on the other side.
7. The rotating anode X-ray tube according to claim 6, wherein the magnetic field is formed by a pair of permanent magnets provided with the bearing gap in between, and the magnets are provided with opposite magnetic poles facing each other.
7. The rotating anode according to claim 6, wherein the magnetic field is formed by permanent magnets arranged on a fixed shaft or a rotating shaft in the tube axis direction, and the permanent magnets are arranged with mutually opposite magnetic poles facing each other. X-ray tube.
The rotating anode X-ray tube according to claim 1, wherein the magnetic fine particles are made of iron oxide particles coated with aluminum or silica.