JP6416593B2 - Rotating anode X-ray tube device and X-ray imaging device - Google Patents

Description

  The present invention relates to a rotary anode X-ray tube device and an X-ray imaging device that reduce rotational vibration of a rotary anode X-ray tube.

  Conventionally, an X-ray tube apparatus is used as an X-ray generation source in medical X-ray apparatuses (X-ray imaging apparatuses) and industrial X-ray inspection apparatuses (X-ray imaging apparatuses) that diagnose a subject using X-rays. It is used.

  As an example, the X-ray tube apparatus has a structure in which an X-ray tube is accommodated in a housing filled with insulating oil, and the X-ray tube is disposed so as to face a cathode that emits thermoelectrons and a cathode. A positive electrode is provided in the vacuum vessel.

  As a kind of X-ray tube device, a rotary anode X-ray tube device having a rotary anode type X-ray tube is known. In a rotating anode type X-ray tube, electrons emitted from the cathode are accelerated and focused by a potential gradient between the cathode and the anode target, and collide with the surface of the rotating X-ray emitting layer of the anode target substantially perpendicularly. Form the focal point that will be the source. When an electron beam with high energy collides with the focal point, the electron beam is rapidly decelerated by the X-ray emitting layer, and X-rays are emitted. The rate of conversion to X-rays is about 1% of the kinetic energy of the electrons that collide with the X-ray emitting layer, and the remaining energy is converted to heat, which heats the anode target and its surroundings.

  When heat is concentrated in the target electron beam spot, the target electron beam spot may be melted by the heat. In the rotating anode X-ray tube device, the electron beam spot on the target is changed by rotating the anode. It is dispersed to prevent heat from being concentrated in the target electron beam spot.

  By the way, the rotary anode X-ray tube apparatus has a structure in which the rotary anode is supported by the vacuum vessel via a bearing such as a ball bearing. Therefore, vibration may occur when the rotating anode rotates due to backlash of parts, residual unbalance, bearing clearance, and the like.

  When the rotating anode vibrates, the vibration is propagated to the vacuum vessel via the supporting means supporting the rotating anode, and further propagated to the housing via the X-ray tube attaching means. For this reason, the housing vibrates and the resolution of the X-ray image is lowered or noise is generated.

  The ball bearing also has a role of transmitting heat of the rotating anode to the outside, and high heat conductivity and heat resistance are required.

  As a background art in this technical field, there is an X-ray tube apparatus described in Patent Document 1.

  In this X-ray tube device, a liquid metal is filled in the gap between the outer ring of the rolling bearing and the bearing housing. When the liquid metal is pushed away by the generated vibration, a reaction force is generated due to the viscosity of the liquid metal (squeeze film damper effect), and a vibration damping effect is obtained. Further, mercury, gallium, gallium alloys, and the like are listed as liquid metals, and all have boiling points of 1000 ° C. or higher, and can be used even under high temperature conditions.

JP 2014-86163 A

  However, although the X-ray tube apparatus described in Patent Document 1 can be used under high temperature conditions, the liquid metal at room temperature is an alloy containing, for example, a gallium heavy metal, and may corrode other members. There is. Moreover, it is necessary to seal so that the liquid metal does not leak, and it is difficult to improve the manufacturing efficiency.

  Therefore, an object of the present invention is to provide a rotary anode X-ray tube device and an X-ray imaging device that are free from corrosion of other members and have high manufacturing efficiency.

  A rotating anode X-ray tube device according to the present invention includes a cathode member that generates an electron beam, an anode member that generates an X-ray when the electron beam collides, a rotating member that supports the anode member, and the rotating member. A bearing box rotatably supported via a bearing, and a container containing the cathode member, the anode member, the rotating member, and the bearing box in a vacuum-tight manner, and the rolling bearing has an axial direction of the rotating member. Is disposed at least on the anode member side, and a gap is formed between the outer ring of the rolling bearing and the inner surface of the bearing box, and an elastic body made of a solid metal material is provided in the gap. Yes.

  Further, the X-ray imaging apparatus is provided with such a rotary anode X-ray tube apparatus.

  According to the present invention, it is possible to obtain a rotary anode X-ray tube device and an X-ray imaging device that do not corrode other members and have high manufacturing efficiency.

It is sectional drawing which shows the rotary anode X-ray tube apparatus which concerns on 1st Embodiment of this invention. It is an expanded sectional view showing the rotation anode X-ray tube concerning a 1st embodiment of the present invention. It is an expanded sectional view of the bearing part concerning a 1st embodiment of the present invention. It is an axis perpendicular cross section of the bearing part concerning a 1st embodiment of the present invention. It is a schematic block diagram which shows the X-ray CT apparatus as an X-ray imaging apparatus. FIG. 6 is a cross-sectional view perpendicular to the axis of a bearing portion according to a second embodiment of the present invention. It is the figure seen in the axial direction of the bearing part of the rotating anode X-ray tube apparatus which concerns on 2nd Embodiment of this invention. It is an axis perpendicular sectional view of a bearing part concerning a 3rd embodiment of the present invention.

Hereinafter, the rotary anode X-ray tube apparatus according to the present embodiment will be described with reference to the drawings.
(First embodiment)
As shown in FIG. 1, the rotary anode X-ray tube device 1 includes a rotary anode X-ray tube 2 inside. The rotating anode X-ray tube 2 includes a cathode member (hereinafter referred to as a cathode body) 3 that generates an electron beam, an anode member (hereinafter referred to as an anode target) 4 that generates an X-ray upon collision with an electron beam, and an anode target. The bottomed cylindrical drive motor rotor 5 that serves as a rotating member that supports the shaft 4, the shaft 6 connected to the drive motor rotor 5, the rolling bearings 10A and 10B that support the shaft 6, and the shaft via the rolling bearings 10A and 10B And a glass tube ball as a container containing the cathode body 3, the anode target 4, the drive motor rotor 5, the shaft 6 (rolling bearings 10A and 10B) and the bearing box 7 in a vacuum-tight manner. 8 and so on.

  The rotary anode X-ray tube 2 is fixed in a housing 9 that forms an outer frame of the rotary anode X-ray tube device 1. A frame 9a protrudes from one end portion inside the housing 9 in the axial direction of the rotary anode X-ray tube 2, and a support portion 9b is fixed to the frame 9a. The rotary anode X-ray tube 2 is fixed to the support portion 9b with a bolt 11. The other end of the rotary anode X-ray tube 2 (glass tube bulb 8) is supported by the housing 9 via a tube support 12.

  The frame 9a is provided with a motor stator 3a serving as a magnetic field generator, and the drive motor rotor 5 and the anode target 4 rotate in the range of 3000 to 9000 rpm by the generation of the rotating magnetic field. When X-rays are generated, a high voltage is applied between the cathode body 3 and the anode target 4, so that the housing 9 is filled with an insulating oil 13 in order to ensure overall electrical insulation.

  As shown in FIG. 2, the shaft 6 is fixed to the bottom of the drive motor rotor 5 with a bolt (not shown) via a flange 6a.

  The bearing box 7 includes a base portion 7a, a cylindrical portion 7b provided integrally with the base portion 7a, and a bearing box surrounding material 16 that covers the cylindrical portion 7b. Bolt holes 7c are formed in the base portion 7a. The bolt 11 for fixing to the support part 9b (refer FIG. 1) is fastened by the bolt hole 7c. Inside the cylindrical part 7b, the shaft 6 is rotatably supported via rolling bearings 10A and 10B.

  The rolling bearings 10 </ b> A and 10 </ b> B are arranged at predetermined intervals via a cylindrical spacer ring 14 in the axial direction of the shaft 6. The spacer ring 14 is positioned and fixed in a non-rotatable manner with a screw or the like (not shown) with respect to the cylindrical portion 7 b of the bearing housing 7.

  The outer peripheral surface of the cylindrical portion 7 b is covered with a cylindrical bearing box surrounding material 16. The bearing box surrounding member 16 has a stepped shape corresponding to the stepped shape of the cylindrical portion 7b, and extends toward the anode target 4 so that the tip end portion 16a covers the bearing 10A.

  As shown in FIG. 3, the rolling bearing 10 </ b> A includes an outer ring 101 and rolling elements (balls) 102. 10 A of rolling bearings do not have an inner ring | wheel, but the groove | channel 6b where the rolling element 102 slidably contacts is formed in the outer peripheral surface of the axis | shaft 6. As shown in FIG. Although not shown, the outer ring 101 is fixed to the spacer ring 14 by a fixing member such as a pin and is fixed so as not to rotate. The bearing housing 7 facing the outer peripheral surface 101 a of the outer ring 101 has a stepped shape, and a gap is provided between the outer peripheral surface 101 a of the outer ring 101 and the inner peripheral surface 7 d of the bearing housing 7. . Therefore, the bearing box 7 has a structure in which the inner diameter is increased (the thickness is reduced) at the end when viewed from the direction of the target 4.

  The outer ring 101 has a shape that increases in thickness in the longitudinal direction of the shaft 6 as it moves away from the anode target 4, and has a structure that becomes thinner toward the target 4 side (left side in FIG. 3). By having this structure, a sufficient fastening surface with the spacer ring 14 can be secured, and the rolling element 102 can be easily inserted into the groove 6b after the outer ring 101 and the shaft 6 are installed. Although the outer ring 101 and the spacer ring 14 are depicted as separate members in FIG. 3, they may be configured by a single member.

  As shown in FIG. 4, between the outer peripheral surface 101a of the outer ring 101 and the inner peripheral surface 7d of the bearing housing 7, a ring (hereinafter referred to as a bump foil) 18 formed by bending a metal band in a wave shape extends in the circumferential direction. Is provided. In other words, the outer ring 101 of the rolling bearing 10 </ b> A is supported by the bearing housing 7 and the inner peripheral surface of the bearing housing enclosure 16 via the bump foil 18.

  The stepped step of the bearing box 7 is formed in the longitudinal direction of the shaft 6 so as to be about the same as or longer than the bump foil 18. In the direction of the shaft 6, it is desirable that the lengths of the bump foil 18 and the outer ring 101 are approximately the same. By having such a shape relationship, the bump foil 18 and the outer ring 101 are easily disposed at an appropriate location by being disposed at the stepped portion of the stepped shape of the bearing box 7, so that the manufacturability is improved. improves.

  In the present embodiment, since the bearing housing 7 has a stepped shape, a gap is formed between the end portion of the bearing housing 7 on the target 4 side and the outer ring 101, and this clearance is used as an installation space for the bump foil 18. It was. However, the present invention is not limited to this, and if there is sufficient space between the shaft 6 and the bearing housing 7, the spacer ring 14 is sufficiently thicker than the outer ring 101 without forming a stepped shape. It is also possible to provide a space between the outer ring 101 and the bearing housing 7 and to provide the bump foil 18 in this space.

  As shown in FIG. 2, the rolling bearing 10 </ b> B has an outer ring 103 and rolling elements 104. Similarly to the rolling bearing 10A, the rolling bearing 10B does not have an inner ring, and a groove 6c is formed on the outer peripheral surface of the shaft 6 so that the rolling element 104 is in sliding contact therewith. The outer ring 103 is housed in the cylindrical portion 7b of the bearing box 7, and is positioned by a pressing spring 17 and a ring 19 installed inside the cylindrical portion 7b.

  In such a rotary anode X-ray tube device, when the shaft 6 rotates, the rotating body such as the shaft 6 and the drive motor rotor 5 is cantilevered to the frame 9a (see FIG. 1) by a bolt 11 (see FIG. 1) on one end side. Since it is supported in the state, the anode target 4 on the other end side which is the farthest side from this is the portion with the largest vibration. Therefore, in the shaft 6, the vibration is greatest at the portion supported by the rolling bearing 10A.

  As shown in FIG. 3, the vibration of the shaft 6 is propagated from the rolling element 102 to the outer ring 101, and is transmitted from the outer ring 101 to the bearing box 7 through the bump foil 18. When vibration is propagated to the bump foil 18, sliding friction is generated between the bump foil 18 and the outer peripheral surface 101a of the outer ring, and vibration energy is dissipated, so that a vibration damping effect is obtained.

  Next, an X-ray CT apparatus as an X-ray imaging apparatus using the rotary anode X-ray tube apparatus 1 will be described with reference to FIG.

  As shown in FIG. 5, the scanner gantry 111 has a circular opening 113 in the center, and a bed 115 for laying the subject 114 is installed in the opening 113. The bed 115 is movable in the body axis direction and the vertical direction of the subject 114 by a horizontal movement unit and a vertical movement unit (not shown).

  A scanner 112 that rotates around the subject 114 is provided in the scanner gantry 111. The rotary anode X-ray tube device 1 and the X-ray detector 116 are arranged on the scanner 112 so as to face each other with the subject 114 interposed therebetween.

  X-rays generated from the rotary anode X-ray tube device 1 are irradiated to the subject 114. A well-known collimator (not shown) or the like is disposed between the irradiation surface side of the rotary anode X-ray tube apparatus 1, that is, between the rotary anode X-ray tube apparatus 1 and the subject 114, and the irradiation field of the X-ray beam is X. A predetermined width corresponding to the line detector 116 is set.

  The X-ray detector 116 is formed in an arc shape centered on the focal point of the rotary anode X-ray tube apparatus 1. On the X-ray receiving surface, a large number of X-ray detection element groups are arranged in a channel direction perpendicular to the body axis of the subject 114, and a plurality of X-ray detection element groups are arranged in the body axis direction of the subject 114. It becomes the composition. The X-ray detector 116 detects X-rays transmitted through the subject 114 and the data acquisition device 117 collects data as projection data.

  The projection data collected by the data collection device 117 is sent to the image reconstruction device 118, and the image reconstruction device 118 reconstructs a tomographic image of the subject 114 based on the projection data. Then, the reconstructed tomographic image is displayed on the image display device 119 and used for image diagnosis.

  According to the rotary anode X-ray tube device 1 of the present embodiment described above, the bump foil 18 that is a solid metallic elastic body is provided between the outer peripheral surface 101a of the outer ring 101 and the inner peripheral surface 7d of the bearing box. Therefore, a vibration damping effect is obtained in which vibration energy is dissipated by sliding friction between the bump foil 18 and the outer ring outer peripheral surface 101a. Accordingly, the rotational vibration can be suitably attenuated to improve the bearing life, and stable rotation can be obtained over a long period.

  Further, in the rolling bearing 10A in which the vibration is greatest in the shaft 6 during operation, the rotational vibration can be suitably reduced by the bump foil 18, so that the rotary anode X-ray tube device 1 having a high vibration damping effect and quiet can be obtained. Can be provided.

  Moreover, since the bump foil 18 is a solid metal, the corrosion of other members which is a concern when a liquid metal that is a heavy metal is provided does not occur. Further, it is not necessary to provide a sealing member as in the case of using liquid metal, and it becomes possible to improve manufacturability. Improvement in manufacturability leads to cost reduction.

  When X-rays are emitted from the surface of the anode target 4 in the direction of the arrow in FIG. 1, a part of the heat generated in the anode target 4 is transferred to the bearing box 7 through the shaft 6 and the rolling bearing 10A by heat conduction. As a result, the rolling bearing 10A will rise to a temperature of about 300 to 400 ° C., but if a metal having a melting point higher than that is used, it will not be melted by the heat of the anode target 4, The attenuation function is not lost within the specified temperature range of the rotary anode X-ray tube 2. Further, if a metal having high thermal conductivity is used for the bump foil 18, the heat dissipation of the shaft 6 can be ensured, so that the rotational vibration is suitably damped and the strength of the metal material used. Since the decrease can be prevented and the bearing life can be improved, stable rotation can be obtained in the long term.

  Further, since the grooves 6b and 6c are provided on the outer peripheral surface of the shaft 6, the inner ring of the rolling bearings 10A and 10B is not required, and the shaft 6 can be formed thicker as much as the inner ring is unnecessary. This contributes to improvement of vibration damping. In addition, since the bearing box 7 has a stepped shape as shown in FIG. 3, a space for arranging the metal elastic body is formed on the outer diameter side of the outer ring 101, so that the shaft 6 can be formed thick. And contributes to the improvement of vibration damping.

Moreover, according to the X-ray CT apparatus using the rotary anode X-ray tube apparatus 1, the noise of the X-ray CT apparatus based on the rotational vibration of the rotary anode X-ray tube apparatus 1 can be suitably reduced, and the quietness is achieved. Improvements can be made. Furthermore, an X-ray CT apparatus capable of improving the resolution of the X-ray image is obtained by attenuating the rotational vibration of the rotary anode X-ray tube apparatus 1.
(Second Embodiment)
A rotary anode X-ray tube apparatus according to a second embodiment will be described with reference to FIGS.

  This embodiment is different from the first embodiment in that the outer ring outer peripheral surface 101a and the inner peripheral surface 7d of the bearing housing 7 are filled with powder 20 (particulate heat transfer material) having high thermal conductivity. It is.

  As shown in FIG. 7, the heat generated in the anode target 4 is transmitted to the shaft 6, and is transferred from the rolling element 102 to the bearing box 7 through the bump foil 18, and is radiated to the outside. At this time, if the contact area between the bump foil 18 and the outer ring outer peripheral surface 101a is small, it is considered that heat cannot be sufficiently transmitted. In this embodiment, the gap between the outer peripheral surface 101a of the outer ring and the inner peripheral surface 7d of the bearing housing 7 is filled with powder 20 having high thermal conductivity. Therefore, the thermal conductivity in the gap can be increased without increasing the bearing radial spring constant of the pump foil. Thereby, since the heat dissipation to the exterior of the bearing box 7 can be improved, the strength reduction by the temperature rise of a bearing material can be prevented. Here, a nitrided ceramic or aluminum is used as a powder having high thermal conductivity.

According to the rotary anode X-ray tube device 1 of the present embodiment, since the material strength can be prevented from being lowered due to excessive temperature, the bearing life can be improved, and stable rotation can be obtained in the long term.
(Third embodiment)
A rotary anode X-ray tube apparatus according to a third embodiment will be described with reference to FIG.

  The present embodiment differs from the first and second embodiments in that it is not a bump foil 18 but a solid metallic elastic body between the outer peripheral surface 101a of the outer ring 101 and the inner peripheral surface 7d of the bearing housing 7. That is, a member filled with more than the number of metal wires 15 in an annular shape is disposed.

  As shown in FIG. 8, a metal wire 15 is filled between the outer peripheral surface 101 a of the outer ring 101 and the inner peripheral surface 7 d of the bearing housing 7. The metal wires 15 are tangled so as to contact each other. When vibration is propagated to the entangled metal wire 15 and a force is applied, the metal wire 15 generates sliding friction between the outer ring outer peripheral surface 101a and between the metal wires, and the vibration energy is dissipated. A vibration damping effect can be obtained.

  Further, by filling the metal wire 15, the contact area between the metal wire 15 and the outer peripheral surface 101 a of the outer ring and the inner peripheral surface 7 d of the bearing housing 7 can be increased as compared with the first embodiment. Can be further enhanced. Even in this case, it is possible to further improve the heat dissipation while maintaining the vibration damping effect by the metal wire 15 by filling the particulate heat transfer material at an appropriate density as in the second embodiment. Is also possible.

  According to the rotating anode X-ray tube device 1 of the present embodiment, it is possible to prevent a decrease in material strength due to excessive temperature, and it is possible to improve the bearing life by suitably attenuating rotational vibration, and thus stable for a long period of time. Rotation is obtained.

  Although the present invention has been described above, the present invention is not limited to the embodiment described above, and can be implemented with appropriate modifications.

  In each of the above embodiments, the bump foil 18 or the metal wire 15 is provided between the outer peripheral surface 101a of the outer ring 101 and the inner peripheral surface 7d of the bearing housing 7. However, the present invention is not limited to this. A ring member having a thickness may be provided between the ring member 7 and the outer ring 101, and the bump foil 18 or the metal wire 15 may be provided between the ring member and the outer ring to form one rolling bearing module. By making the bearing modular, it is possible to further improve the manufacturability.

  Further, although the grooves 6b and 6c are formed on the outer peripheral surface of the shaft 6, the present invention is not limited to this, and an inner ring may be provided to support the shaft 6 with the inner ring.

  Further, the rotary anode X-ray tube apparatus 1 described in each of the embodiments is not limited to the one used for the above-described X-ray CT apparatus, and may be used for an industrial X-ray inspection apparatus as an imaging apparatus. it can. Also in this case, the quietness can be improved and the resolution of the X-ray image can be improved by the rotational vibration damping effect of the rotary anode X-ray tube apparatus 1.

DESCRIPTION OF SYMBOLS 1 Rotating anode X-ray tube apparatus 2 Rotating anode X-ray tube 3 Cathode body (cathode member)
4 Anode target (anode member)
6 axis (rotating member)
7 Bearing box 8 Glass tube (container)
10A Rolling bearing 10B Rolling bearing 14 Spacer ring 15 Metal wire 16 Bearing box envelope 18 Bump foil 20 Powder 101 Outer ring

Claims (5)

A cathode member for generating an electron beam;
An anode member that generates X-rays when an electron beam collides;
A rotating member that supports the anode member;
A bearing box that rotatably supports the rotating member via a rolling bearing;
A container containing these cathode member, anode member, rotating member, and bearing box in a vacuum-tight manner; and
A gap is formed between the outer ring of the rolling bearing and the inner surface of the bearing housing,
A rotary anode X-ray tube device in which an elastic body containing a solid metal material is provided in the gap, and the gap in which the elastic body is installed is filled with a particulate heat transfer material . The rotary anode X-ray tube device according to claim 1,
The rotary anode X-ray tube device, wherein the elastic body is formed by filling a metal wire. The rotary anode X-ray tube device according to claim 1,
The rotating anode X-ray tube device according to claim 1, wherein the rotating member has an annular groove on an outer peripheral surface on which a rolling element constituting the rolling bearing is arranged and slides. The rotary anode X-ray tube device according to claim 1,
The bearing housing has a stepped shape with an inner diameter increasing toward the anode member side, and the gap is formed between the stepped shape and the rolling bearing. Tube device.   An X-ray imaging apparatus comprising the rotary anode X-ray tube apparatus according to claim 1.