JP2003217492A - Rotary positive electrode type x-ray tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary positive electrode type X-ray tube preventing leakage of a liquid metal antifriction to the inside space of a vacuum vessel. <P>SOLUTION: This rotary positive electrode type X-ray tube is provided with: a positive electrode target 12 disposed in the vacuum vessel 11; and a rotary support mechanism 15 equipped with a dynamic pressure type sliding bearing using the liquid metal antifriction for rotatably supporting the target 12. The X-ray tube is characterized in that the support mechanism 15 has at least two inside cylinders 17 and a thrust ring 20 having surfaces coming into contact with each other in a predetermined area, and a metallic sealing member 101 easily wetted by the liquid metal antifriction is disposed between the inside cylinder 17 and the thrust ring 20 and in the vicinity of the predetermined area. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary anode type X in which liquid metal lubricant is prevented from leaking into the internal space of a vacuum container.
Regarding the wire tube.

[0002]

2. Description of the Related Art A rotary anode X-ray tube is an electron tube that emits X-rays and has a structure in which an anode target placed in a vacuum container is irradiated with an electron beam to emit X-rays. The anode target is rotatably supported by a rotation support mechanism so that it can rotate at a high speed when emitting X-rays. The rotation support mechanism is composed of a rotating portion and a fixed portion that are fitted to each other, and a bearing portion is provided at both fitting portions.

The bearing portion is a rolling bearing such as a ball bearing, or a spiral groove is formed on the bearing surface to form gallium (Ga) or gallium-indium-tin (Ga-In).
-Sn) A dynamic pressure type slide bearing or the like that supplies a liquid metal lubricant that becomes liquid during operation to the spiral groove portion, such as an alloy.

An example using a dynamic pressure type slide bearing is disclosed in Japanese Patent Laid-Open No.
0-117531 and JP-A-2-227948,
It is disclosed in Japanese Patent Laid-Open Nos. 5-13028 and 7-192666.

[0005]

The rotary anode type X-ray tube is
When a hydrodynamic slide bearing is used, a liquid metal lubricant is supplied to the bearing portion. In addition, during operation, the anode target rotates at a high speed of 3000 rpm to 9000 rpm, and its orientation also changes depending on the usage state. Therefore, regardless of the posture of the X-ray tube, the liquid metal lubricant can be supplied to the spiral groove portion of the dynamic pressure type slide bearing in a proper amount for a long period of time.

Further, if the liquid metal lubricant leaks from the bearing to the space inside the vacuum container, the withstand voltage performance of the X-ray tube is impaired, which causes discharge. Therefore, a sealing structure is adopted so that the liquid metal lubricant does not leak into the space inside the vacuum container.

However, when the gas remaining in the space of the bearing portion or the gas contained in the bearing member is released to generate gas bubbles, the pressure of this gas causes the liquid metal lubricant to be ejected into the internal space of the vacuum container. There are cases.

Further, the posture of the rotary anode type X-ray tube changes,
When the load applied to the bearing changes, the relative position between the rotating body and the fixed body changes, and the pressure distribution changes. As a result, the flow of the liquid metal lubricant may be directed toward the internal space of the vacuum container and may leak into the internal space.

Further, a rotary support mechanism for supporting the anode target, such as a rotary body or a fixed body, is generally constructed by combining a plurality of constituent parts. Therefore, in the manufacturing process, the liquid metal lubricant may adhere to the fastening surfaces where the surfaces of a plurality of components contact each other, and the liquid metal lubricant adhering to the fastening surfaces leaks into the internal space of the vacuum container. Sometimes.

Japanese Unexamined Patent Publication No. 2000-173518 discloses a method of making a bearing surface and a fastening surface different from each other so that the liquid metal lubricant does not adhere to the fastening surfaces of a plurality of components. However, this method cannot detect even if the liquid metal lubricant adheres to the fastening surface because the fastening surfaces of multiple components are invisible to the operator, and leakage of the liquid metal lubricant is completely prevented. Can not.

Further, there is a method of sandwiching and fixing a soft metal between the fastening surfaces of a plurality of constituent parts. In this method, when the soft metal is deformed, the positional relationship between the components shifts,
The dimensional accuracy decreases and the bearing characteristics become unstable.

As described above, in the conventional rotary anode type X-ray tube, the liquid metal lubricant leaks into the internal space of the vacuum container during the operation or the like, and the withstand voltage performance of the X-ray tube is impaired, resulting in the occurrence of discharge. May cause.

It is an object of the present invention to solve the above-mentioned drawbacks and to provide a rotating anode type X-ray tube in which the liquid metal lubricant is prevented from leaking into the internal space of a vacuum container.

[0014]

According to the present invention, there is provided an anode target arranged in a vacuum container, a hydrodynamic slide bearing using a liquid metal lubricant, and a rotation support mechanism for rotatably supporting the anode target. Rotating anode type X equipped with
In the wire tube, the rotary support mechanism has at least two first and second components whose surfaces are in contact with each other in a predetermined region, and between the first component and the second component. In addition, a sealing member made of a metal that easily wets the liquid metal lubricant is arranged in the vicinity of the predetermined region.

[0015]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to FIG.

Reference numeral 11 is a vacuum container constituting an X-ray tube,
In the figure, a part thereof is shown. In the vacuum container 11, X
An anode target 12 for generating lines is arranged. The anode target 12 is fixed to the rotating column 14 by a nut 13. The rotary column 14 is connected to a rotary support mechanism 15, and the anode target 12 is rotatably supported by the rotary support mechanism 15.

The rotation support mechanism 15 is composed of a rotating portion and a fixed portion. The rotating part is, for example, the rotating column 14.
An intermediate cylinder 16 made of iron alloy having a substantially bottomed cylindrical shape to which is directly adhered, an inner cylinder 17 arranged inside the intermediate cylinder 16 with a first heat insulating gap Ga, and a second outside the intermediate cylinder 16. It is composed of a three-layer structure of a copper outer cylinder 18 arranged with a heat insulating gap Gb. Inner cylinder 17
The intermediate cylinder 16 and the outer cylinder 18 are partially joined to each other adjacent to each other.

A fixed body 19 made of an iron alloy and having a substantially cylindrical shape is fitted and inserted into the inside of the inner cylinder 17. Fixed body 1
Reference numeral 9 indicates, for example, a first small diameter portion 19a having a small diameter located above the drawing, a large diameter portion 19b having a large diameter located in the middle of the drawing, and a diameter larger than the large diameter portion 19b than the first small diameter portion 19a. Is also formed from a second small diameter portion 19c having a small diameter and located in the lower part of the drawing.

A thrust ring 20 is provided so as to substantially close the lower end opening of the inner cylinder 17.
The thrust ring 20 is fixed to the inner cylinder 17 with, for example, a screw S, and constitutes a rotating portion that rotates integrally with the inner cylinder 17.

Inner cylinder 17 constituting the rotation support mechanism 15
A dynamic pressure type slide bearing is provided at a fitting portion between the fixed body 19 and the fixed body 19. For example, on the outer peripheral surface of the first small diameter portion 19a of the fixed body 19, dynamic pressure generating grooves for generating dynamic pressure, for example, herringbone pattern spiral grooves 21 and 22 are formed in two pairs at axially distant positions, respectively. Together with the inner peripheral surface of the cylinder 17, dynamic pressure type slide bearings 23 and 24 in the radial direction are formed.

Further, a dynamic pressure generating groove for generating a dynamic pressure, for example, a circular herringbone pattern spiral groove 26 is formed on the upper surface 25 of the large diameter portion 19b of the fixed body 19 as shown in FIG. Together with the step surface, a dynamic pressure type slide bearing 27 in the thrust direction is configured. A circular herringbone pattern spiral groove 29 is also formed on the upper surface 28 of the thrust ring 20, and a dynamic pressure type sliding bearing 30 in the thrust direction is configured with the lower surface of the large-diameter portion 19b, which faces the spiral groove 29 in close proximity to the groove.

A part having a small outer diameter is provided in a part of the fixed body 19, for example, a region sandwiched by radial dynamic pressure type slide bearings 23 and 24, to form an annular storage space 31 for storing the liquid metal lubricant. ing. Further, on the outer peripheral surface of the fixed body 19, openings 32a to 32d of each of a plurality of passages for supplying the liquid metal lubricant to the spiral groove and the bearing gap of the dynamic pressure type slide bearing are provided at predetermined intervals in the axial direction. ing.

Below the thrust ring 20, a plurality of trap rings 33, 3 for preventing the liquid metal lubricant from leaking out.
4 is fixed.

The outer peripheral portion of the second small diameter portion 19c of the fixed body 19 is hermetically welded to the inside of the sealing metal ring 35, and the outside of the sealing metal ring 35 is sealed to the glass portion of the vacuum container 11. There is.

In the above construction, the dynamic pressure type slide bearings 23, 24, 27, 3 in the radial direction and the thrust direction are provided.
0, the dynamic pressure type slide bearing closest to the space 11a in the vacuum container, for example, the dynamic pressure type slide bearing 30 in the thrust direction.
A dynamic pressure generating portion 36 is formed on the outer peripheral surface of the second small diameter portion 19c that is coaxially opposed to the thrust ring 20 on the way to the space 11a in the vacuum container.

The dynamic pressure generating portion 36 is composed of a plurality of spiral grooves 37 of a predetermined length provided in a direction inclined with respect to the tube axis, and the spiral grooves 37 are provided at predetermined intervals in the circumferential direction. When the rotating body of the rotating mechanism 15 is rotated, the plurality of spiral grooves 37 are formed on the liquid metal lubricant from the side of the space 11a in the vacuum container located below in the figure to the dynamic pressure type slide located above in the figure. The pressure for moving to the bearings 23, 24, 27, 30 side, so-called dynamic pressure is generated.

A thin portion 20a having a small wall thickness is provided on the outer peripheral portion of the thrust ring 20. Thin part 20a
As a result, an annular sealing space 100 is formed between the lower end surface of the inner cylinder 17 and the thrust ring 20, and an annular sealing member 101 for preventing the liquid metal lubricant from leaking into the sealing space 100. Is fixed.

Here, a structure in which the vicinity of the sealing space 100 is extracted will be described with reference to FIG. 2 is shown in FIG.
The same reference numerals are given to the portions corresponding to, and the overlapping description will be partially omitted.

A thin portion 20a having a small thickness is formed on the outer peripheral portion of the thrust ring 20. At this time, the thin portion 2
An annular sealing space 100 is formed in the upper part of 0a. In addition, the inner surface of the thin portion 20a, for example, the thick portion 20b adjacent to the tube axis m side thereof, and the lower end surface 17a of the inner cylinder 17 form a fastening surface that makes contact with each other. An annular sealing member 101 that prevents the liquid metal lubricant from leaking is fixed in the sealing space 100 by using, for example, elastic deformation. The sealing member 101 is formed of a material that is easily wetted by the liquid metal lubricant, such as copper or copper alloy.

As shown in FIG. 3, the sealing member 101 is formed, for example, in a substantially cylindrical shape, and the opening diameter of the upper end 101a in the drawing is smaller than the opening diameter of the lower end 101b in the drawing. The length L is set to be slightly larger than the length of the sealing space 100 in the tube axis direction.

The sealing member 101 having the above-described structure is placed in the sealing space 100, and then the inner cylinder 17 and the thrust ring 20 are fixed with the screw S. At this time, the inner cylinder 1
The sealing member 101 is sandwiched between the 7 and the thrust ring 20 and is elastically deformed and fixed by being applied with a force from above and below.

According to the above-mentioned structure, the pressure of the gas remaining in the spaces of the dynamic pressure type slide bearings 23, 24, 27 and 30 or the pressure of the gas released from the bearing member, or the inside of the bearing due to the change of the attitude of the bearing, etc. Even if the liquid metal lubricant flows toward the space 11a in the vacuum container 11 due to the pressure change, the dynamic pressure of the spiral groove 37 suppresses the flow, and the liquid metal lubricant is prevented from leaking.

In addition, a sealing member 101, in which the liquid metal lubricant is easily wetted, is arranged in the sealing space 100. Therefore, the liquid metal lubricant that leaks from the fastening surface between the inner cylinder 17 and the thrust ring 20 adheres to the sealing member 101 and is prevented from leaking into the space 11a in the vacuum container 11.

In the above embodiment, the thrust ring is provided with a thin portion, and the sealing space is formed on the thrust ring side. However, a recess may be provided in the inner cylinder to form the sealing space on the side of the inner cylinder, or the sealing space may be formed across both.

In the above embodiment, the sealing space is provided at the end of the inner cylinder located on the side far from the anode target. However, when the end opening of the inner cylinder close to the anode target is sealed with a disk-shaped member or the like, a sealing space having the above-described structure is formed in these parts and the sealing member is arranged. You can also

Further, in the above embodiment, the sealing member is arranged outside the joint surface between the inner cylinder and the thrust ring, for example, on the side far from the pipe axis. In this case, since the position of the sealing member is close to the space inside the vacuum container, degassing in the vicinity of the sealing member becomes easy. However, even when the sealing member is arranged inside the joint surface, the liquid metal lubricant adheres to the sealing member,
The amount and pressure of the liquid metal lubricant are reduced, and the effect of preventing the liquid metal lubricant from leaking from the joint surface can be obtained.

[0037]

According to the present invention, it is possible to realize a rotary anode type X-ray tube which prevents leakage of the liquid metal lubricant into the internal space of the vacuum container.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining an embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining the vicinity of the sealing space according to the embodiment of the present invention.

FIG. 3 is a perspective view illustrating a sealing member used in the embodiment of the present invention.

[Explanation of symbols]

11 ... Vacuum container 12 ... Anode target 13 ... Nut 14 ... Rotating support 15 ... Rotation support mechanism 16 ... Intermediate cylinder 17 ... Inner cylinder 18 ... Outer cylinder 19 ... Fixed body 20 ... Thrust ring 21 ... spiral groove 22 ... Helical groove 23 ... Radial dynamic pressure type slide bearing 24 ... Radial dynamic pressure type slide bearing 25 ... Upper bearing surface of large diameter part of fixed body 26 ... Herringbone pattern spiral groove 27 ... Dynamic pressure type slide bearing in thrust direction 28 ... Upper bearing surface of thrust ring 29 ... Herringbone pattern spiral groove 30 ... Dynamic pressure type sliding bearing in thrust direction 100 ... Sealing space 101 ... Sealing member

Claims (5)

[Claims] 1. A rotary anode type X-ray comprising an anode target arranged in a vacuum container, a dynamic pressure type sliding bearing using a liquid metal lubricant, and a rotary support mechanism for rotatably supporting the anode target. In the tube, the rotary support mechanism has at least two first and second components whose surfaces are in contact with each other in a predetermined area,
Between the first component and the second component, and in the vicinity of the predetermined region, a sealing member made of a metal that easily wets the liquid metal lubricant is arranged. X-ray tube. 2. The rotary anode type X-ray tube according to claim 1, wherein a sealing member is arranged on an outer side of the predetermined area far from the tube axis. 3. The at least one of the first component and the second component is provided with a recessed portion that is recessed with respect to the surfaces in contact with each other, and a sealing member is arranged in the recessed portion.
Alternatively, the rotary anode type X-ray tube according to claim 2. 4. The rotating anode type X-ray tube according to claim 1, wherein the sealing member is made of copper or a copper alloy. 5. The rotary anode according to claim 1, wherein the sealing member is elastically deformed and sandwiched between the first component and the second component. Type X-ray tube.