JPWO2014034632A1 - Rotating anode type X-ray tube apparatus and X-ray imaging apparatus - Google Patents

Abstract

It is an object of the present invention to provide a preload structure that does not cause a preload required for a rotary anode type X-ray tube device, that is, a time delay due to heat conduction and does not overload. A rotary anode type X-ray tube apparatus including a cathode and a rotary anode, wherein the rotary anode is a rotary body (8a, 8b) that rotates together with the anode target, and a bearing unit for lubricating the rotation of the rotary body ( 10) and a fixed body that rotatably supports the rotating body via the bearing unit (10). The bearing unit (10) includes a plurality of bearings (13) arranged along the axial direction of the rotating body. 17) and one preload structure (14, 16, 207, 208) provided for each bearing, each of the preload structures being in the direction of the rotation axis of the rotating body with respect to each of the bearings. Is applied to the bearing with a preload amount smaller than the load applied to the bearing from the rotating body.

Description

  The present invention relates to a rotary anode type X-ray tube apparatus and an X-ray imaging apparatus, and more particularly to a technique for improving rotational characteristics (vibration, noise, and bearing lubrication performance).

  As an example of a preload structure using thermal expansion, Patent Document 1 discloses that one or more spacers are arranged adjacent to an outer ring or an inner ring of a combined rotary element bearing, and the axial direction of the spacers by heating or cooling. A technique for controlling the preload by increasing or decreasing the size of the sensor is disclosed.

JP 2009-257586

  In the case of the fixed position preload structure using the thermal expansion of the spacer, the result is that the ball is pressed to the same position by the spacer during the thermal expansion. For this reason, in the case of a solid lubricated bearing, there is a possibility that minute wear will occur on the bearing race surface, particularly during the initial running-in operation.

  Furthermore, the spacer is heated to 100 to 200 ° C. when X-rays are generated, and the temperature changes depending on the load condition. For this reason, in the method of controlling the preload using the spacer thermal expansion disclosed in Patent Document 1, it is difficult to control the axial gap (several tens of μm) due to heat from the outside. Further, since a time delay due to the heat capacity of the spacer also occurs, it is difficult to control ball vibration at a high frequency due to high-speed rotational vibration of the rotating anode of the X-ray tube and axial gap change for suppressing it.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a preload structure in which there is no time delay due to heat conduction.

  In order to solve the above-mentioned problems, the present invention provides a rotary anode X-ray tube device comprising: a cathode that generates an electron beam; and a rotary anode that includes an anode target that generates X-rays when the electron beam collides. The rotating anode supports a rotating body rotating together with the anode target, a bearing unit for lubricating rotation of the rotating body, and the rotating body rotatably via the bearing unit. A fixed body, and the bearing unit includes a plurality of bearings arranged along a rotation axis direction of the rotating body, and a preload structure provided for each of the bearings. Each of the structures gives the bearing a preload amount smaller than a load applied to the bearing from the rotating body in a state where the rotation axis direction of the rotating body coincides with the direction of gravity. Special To.

  ADVANTAGE OF THE INVENTION According to this invention, the preload structure without a time delay by heat conduction can be provided.

Axial sectional view showing a schematic configuration of a rotary anode type X-ray tube apparatus according to the first embodiment Axial sectional view showing the schematic configuration of the X-ray tube Axial sectional view showing a schematic configuration of the rotating anode 6 (however, from the rotation center axis to the outer edge) Explanatory diagram showing the heat flow path inside the rotating anode (however, from the rotation center axis to the outer edge) Axial sectional view of the bearing unit 10 according to the first embodiment (however, from the rotation center axis to the outer edge) and an enlarged sectional view of the bearing FIG. 2 is an explanatory view showing a bearing structure, in which (a) shows an axial sectional view of the bearing unit 10 and an enlarged view around the bearing, and (b) is a perspective view of the bearing. Explanatory drawing explaining operation of bearing Circumferential sectional view and perspective view showing bearing structure FIG. 7 is a perspective view at the center cross-sectional position of the bearing unit 10 and an explanatory diagram showing the shape of each component, in which the direction in which the anode rotation shaft 7 is located is directed upward in the gravity direction, and the rotation axis direction is parallel to the gravity direction. Indicates the state. FIG. 6 is an explanatory diagram of an axial cross-section showing a preload structure in the bearing unit 10, and the rotation center axis in a state where the direction in which the anode rotation shaft 7 is located is directed downward in the gravity direction and the rotation axis direction is parallel to the gravity direction. To the outer edge. An illustration of an axial section of a bearing unit without preload and without an axial gap, with the direction of the anode rotation shaft 7 facing downward in the direction of gravity and rotation with the rotation axis direction parallel to the direction of gravity Shown from the central axis to the outer edge. It is explanatory drawing of the axial direction cross section which shows the structure of the bearing unit without a preload and an axial gap, Comprising: The direction in which the anode rotating shaft 7 is located turned to the gravity direction lower side, and the rotating shaft direction was made parallel to the gravity direction The state from the rotation center axis to the outer edge is shown. It is explanatory drawing which shows the behavior of a bearing unit with no preload and an axial gap, where (a) shows a state in which an axial load is applied and the first outer ring 203 falls, and (b) shows an axial load. Is applied, but the first outer ring 203 cannot be dropped. Explanatory drawing showing the behavior of a bearing unit with a preload structure and an axial gap only in the upper bearing along the direction of gravity FIG. 4 is an explanatory diagram showing behavior when an axial load is not applied to the bearing unit 10 according to the present embodiment. Explanatory drawing which shows a behavior when the axial direction load is applied to the bearing unit 10 which concerns on this embodiment Cross-sectional view in the axial direction showing a schematic configuration of the X-ray tube according to the second embodiment Axial cross-sectional view showing the schematic configuration of the rotating anode (however, from the rotation center axis to the outer edge) Axial sectional view of the bearing unit 10 adopting the preload structure bearing according to the second embodiment (however, showing from the rotation center axis to the outer edge) Explanatory drawing which shows the behavior of a bearing unit when the axial direction load is not applied to the bearing unit which concerns on 2nd embodiment. Explanatory drawing which shows the behavior of a bearing unit when the axial direction load is applied to the bearing unit which concerns on 2nd embodiment. Functional block diagram showing the overall configuration of the X-ray CT apparatus using the rotating anode type X-ray tube according to the embodiment.

  A rotary anode X-ray tube apparatus according to this embodiment includes a cathode that generates an electron beam, and a rotary anode that includes an anode target that generates an X-ray by collision with the electron beam. The rotating anode includes a rotating body that rotates together with the anode target, a bearing unit that lubricates rotation of the rotating body, and the rotating body that is rotatable via the bearing unit. A fixed body that supports the bearing unit, and the bearing unit includes a plurality of bearings arranged along an axial direction of the rotating body, and a preload structure provided one for each bearing, Each of the preload structures gives the bearing a preload amount smaller than a load applied to the bearing from the rotating body in a state where the rotation axis direction of the rotating body coincides with the direction of gravity. It features that To.

  Each of the bearings has a ball as a rolling element, an inner ring having a bearing curved surface including a contact surface of the ball, and a contact surface with the ball that is located on the opposite side of the inner ring with the ball interposed therebetween. And an outer ring. In this case, the preload structure includes a preload spring that generates a preload, and a preloader disposed between the preload spring and the bearing, and the preload spring is attached to the bearing via the preloader. A preload may be applied.

  The bearing unit may further include a bearing spacer disposed between the two adjacent bearings. In this case, the bearing spacer may be fixed to the fixed body, one end of the preload spring may be supported by the bearing spacer, and the other end may be in contact with the preloader.

  Further, an axial gap is formed along the rotation axis direction between the bearing spacer and the preloader, and the position of the rotary anode is in a state in which the rotation axis direction coincides with the direction of gravity. The preloader included in the preload structure for the bearing located on the upper side along the gravity direction is in contact with the bearing spacer so that the gap width of the axial gap is 0, and the posture of the rotary anode is in the direction of the rotation axis The axial gap may be formed between each of the preloaders included in the preload structure for each of the bearings and the bearing spacer.

  The rotating anode further includes an anode rotating shaft connected to the anode target, and a shaft box that houses the anode rotating shaft and the bearing unit, and the rotating body includes the anode target and the anode rotating. An axis may be included. The fixed body may be included in the axle box.

  As an aspect different from the above, the bearing spacer is fixed between the inner wall surfaces of the axle box and is disposed between two outer rings included in adjacent bearings, and the preloader includes an outer ring of each of the bearings. The one end of the preload spring is disposed between the bearing spacer and the bearing spacer, the other end is in contact with the preloader, and the preload spring is disposed between the bearing spacer and the preloader. The axial gap may be formed. Moreover, the inner ring | wheel of each said bearing may be formed integrally with the said anode rotating shaft.

  The rotating anode may further include a shaft box connected to the anode target and a fixed shaft that rotatably supports the shaft box via the bearing unit. In this case, the axle box may house the bearing unit and the fixed shaft, the rotating body may include the anode target and the axle box, and the fixed body may include the fixed shaft.

  The bearing unit is relatively outer along the radial direction of the fixed shaft and relatively outer along the radial direction of the fixed shaft, and an outer diameter side spacer disposed between the outer rings of the adjacent bearings. And an inner diameter side spacer disposed between the inner rings of the adjacent bearings, and the outer diameter side spacer is fixed to the inner wall surface of the axle box and included in the adjacent bearings. Abutting against two outer rings, the inner diameter side spacer is fixed to the outer surface of the fixed shaft, the preloader is disposed between the inner ring of each bearing and the inner diameter side spacer, and the preload spring is One end may contact the inner diameter side spacer, the other end may contact the respective preloader, and the axial gap may be formed between the inner diameter side spacer and each of the preloaders. As the preload spring, a double coil spring in which a small-diameter coil spring having a relatively small diameter is arranged in a large-diameter coil spring having a relatively large diameter may be used.

  Further, the bearing unit is configured such that two bearings that are paired face each other along the rotation axis direction, and the position of the inner ring or the outer ring is closer to the rotating body than the distance between the centers of the balls of the two bearings. It may be arranged so that the distance between the bearing curved surface and the contact point of the ball is longer. Each of the bearings may be formed using a solid lubricant.

  A rotating anode X-ray tube apparatus according to the present invention includes a cathode that generates an electron beam, and a rotating anode including an anode target that generates an X-ray by collision with the electron beam. The rotating anode includes a rotating body that rotates together with the anode target, a bearing unit that lubricates rotation of the rotating body, and the rotating body that is rotatable via the bearing unit. A plurality of bearings disposed along the axial direction of the rotating body, a preload structure provided for each bearing, and the plurality of adjacent bearing units. Bearings disposed between the bearings, each of the bearings includes a ball as a rolling element, an inner ring having a curved bearing surface including a contact surface of the ball, and the inner ring across the ball. Is on the opposite side and said Each of the preload structures includes a preload spring that generates preload, and a spacer that is disposed between the preload spring and the bearing. The bearing spacer is fixed to the fixed body, one end of the preload spring is supported by the bearing spacer, the other end abuts on the preloader, and the bearing spacer, the preloader, An axial gap along the rotation axis direction is formed between the bearing spacer and the axial length of the bearing spacer in the rotation axis direction even when the bearing spacer is thermally expanded by heat generated from the anode target. The rotary anode is positioned above the gravity direction in a state where the rotation axis direction coincides with the gravity direction. The preloader included in the preload structure for the bearing contacted with the bearing spacer, the gap width of the axial gap became 0, and the orientation of the rotating anode was in the direction in which the direction of the rotating shaft coincided with the horizontal direction In the state, the axial gap is formed between each of the preloaders included in the preload structure for each bearing and the bearing spacer.

  Furthermore, an X-ray imaging apparatus may be configured by including any one of the above-described rotating anode X-ray tube devices and an X-ray control device that applies a high voltage to the rotating anode X-ray tube device.

  Hereinafter, this embodiment will be described in more detail.

  The X-ray tube apparatus according to the present embodiment is a rotating anode X-ray tube apparatus having a so-called rotating anode in which an anode target colliding with an electron beam emitted from the cathode among the anodes in the X-ray tube rotates. It is related to. In order to ensure the X-ray dose required for medical X-ray tube devices, it is necessary to make a large amount of electron beams collide with the anode target, and the focus temperature rise of the X-rays formed on the collision surface becomes significant. By using the rotary anode type X-ray tube device, it is easy to prevent only one portion of the anode target from being heated.

  Hereinafter, the present embodiment will be described with reference to the drawings. The same reference numerals are given to the procedures having the same functions and the same processing contents, and the description thereof will not be repeated.

<First embodiment>
First, the configuration of the first embodiment will be described based on FIG. 1 to FIG. The first embodiment has a tubular structure in which a bearing having an inner ring, a rolling element (ball), and an outer ring is used, and the inner ring rotates to rotate the anode target. FIG. 1 is an axial sectional view showing a schematic configuration of a rotary anode X-ray tube apparatus according to a first embodiment. FIG. 2 is an axial sectional view showing a schematic configuration of the X-ray tube. FIG. 3 is an axial sectional view showing a schematic configuration of the rotary anode 6 (however, from the rotation center axis to the outer edge). FIG. 4 is an explanatory view showing a heat flow path inside the rotating anode (however, from the rotation center axis to the outer edge). FIG. 5 is a sectional view in the axial direction of the bearing unit 10 according to the first embodiment (however, from the rotation center axis to the outer edge) and an enlarged sectional view of the bearing. 6A and 6B are explanatory views showing the bearing structure, in which FIG. 6A is an axial sectional view of the bearing unit 10 and an enlarged view around the bearing, and FIG. 6B is a perspective view of the bearing. FIG. 7 is an explanatory diagram for explaining the operation of the bearing. FIG. 8 is a circumferential sectional view and a perspective view showing a bearing structure. FIG. 9 is a perspective view at the center cross-sectional position of the bearing unit 10 and an explanatory diagram showing the shape of each component, with the direction in which the anode rotation shaft 7 is located facing upward in the direction of gravity and the direction of rotation axis in the direction of gravity It shows the state of being parallel. FIG. 10 is an explanatory diagram of an axial cross section showing a preload structure in the bearing unit 10, with the direction in which the anode rotation shaft 7 is located facing downward in the gravity direction and the rotation axis direction parallel to the gravity direction. From the rotation center axis to the outer edge.

  A rotating anode X-ray tube apparatus shown in FIG. 1 has a rotating anode X-ray tube (hereinafter abbreviated as an X-ray tube) having a cathode 2 and a rotating anode (hereinafter sometimes abbreviated as an anode) 6. 101 and a substantially box-shaped tube container 102 that accommodates the X-ray tube 101. Inside the tube container 102, a stator coil 21 that rotationally drives the X-ray tube 101, a cathode support 106 that insulates and supports the cathode side of the X-ray tube 101, and an anode side of the X-ray tube 101 are insulated. And supporting anode support 103. The anode side end of the X-ray tube 101 is fixed to the anode support 103 using a fixture (for example, an anode fixing screw 104). The stator coil 21 is also fixed to the anode support 103. On the outer periphery of the tube container 102, a cathode-side high-voltage socket 107 that feeds a negative high voltage to the cathode 2 of the X-ray tube 101 and a positive high voltage to the rotating anode 6 of the X-ray tube 101 And an anode-side high-voltage socket 108 for supplying power. The inside of the tube container 102 is filled with an insulating oil 109 for insulation and cooling.

  The tube container 102 is provided with a tube container radiation window 105 for emitting X-rays generated from the X-ray tube 101 to the outside of the tube container 102. Of the inner wall surface of the tube container 102, an X-ray shielding member, for example, a lead plate, for preventing X-rays from leaking is attached to the portion excluding the tube container radiation window 105.

  As shown in FIG. 2, the X-ray tube 101 includes a cathode 2 that generates an electron beam 3, a rotating anode 6 that generates an X-ray 4 when the electron beam 3 from the cathode 2 collides, and a cathode 2 that rotates. And an envelope 1 that encloses and supports the anode 6 in a vacuum-tight manner.

  The cathode 2 is heated to emit an electron beam 3 (not shown), and the electron beam 3 is focused to form a collision surface (referred to as a “focal point”) 5 of the electron beam 3 on the rotating anode 6. A focusing electrode 2a, a holder 2b that supports the focusing electrode 2a, and a stem 2c that supports the holder 2b in an insulated manner are provided. The stem 2c is made of an insulating material such as glass or ceramic, and a plurality of stem leads (not shown) are embedded in the center thereof. The stem lead is connected to the filament, the focusing electrode 2a, and the holder 2b inside the X-ray tube 101, and outside the X-ray tube 101, the cathode lead (not shown) of the cathode side high voltage socket 107 (see FIG. 1). Connected to (omitted). Via this cathode side lead and stem lead, a high voltage with a negative potential is supplied to the focusing electrode 2a and the holder 2b, and a filament heating voltage is supplied to the filament.

  The rotating anode 6 is configured as an assembly including a rotating body that rotates, a fixed body (stationary body) that supports the rotation, and a bearing mechanism that is positioned between the rotating body and the fixed body. The rotating body includes an anode target 7, a rotor 12, a heat insulating part 202, and an anode rotating shaft 8. The fixed body includes a shaft box 9 and a magnetic part 117. Further, as a bearing mechanism, a bearing unit 10 that rotatably supports the anode rotating shaft 8 with respect to the axle box 9 is provided.

  The anode target 7 is disposed opposite to the focusing electrode 2a of the cathode 2, and receives an electron beam 3 from the cathode 2 at a focal point 5 to generate X-rays. The rotor 12 generates rotational torque by a magnetic field from the stator coil 21 and obtains a rotational driving force to rotate. The rotor 12 is configured in a substantially cylindrical shape, one end is sealed, and the other end is open. Then, the surface of the anode target 7 opposite to the surface facing the cathode 2 is opposed to the sealed end surface of the rotor 12, and the rotor 12 is connected to the side of the anode target 7 opposite to the cathode 2 Is done. Inside the rotor 12, the heat insulating part 202 and the anode rotating shaft 8 are accommodated, and the rotor 12 and the anode rotating shaft 8 are connected via the heat insulating part 202, and heat transfer to the anode rotating shaft 8 is reduced. On the other hand, the axle box 9 has a hollow portion that accommodates the bearing unit 10 and has a cylindrical portion 9a that is sealed at the end opposite to the anode target 7, and is opposite to the anode target 7 of the cylindrical portion 9a. A fixed end portion 9b protruding to the side. A part of the anode rotating shaft 8 and the bearing unit 10 are accommodated in the cylindrical portion 9a. The magnetic part 117 is disposed between the outer peripheral part of the axle box 9 and the rotor 12, and is made of a magnetic material that plays a role of collecting a rotating magnetic field from the stator coil 21. Details of the rotating anode 6 will be described later.

  The envelope 1 is located in the center of the envelope 1, and includes a large diameter portion 1a that encloses the anode target 7, a cathode insulating portion 1b that insulates and supports the cathode 2, and an anode insulating portion that insulates and supports the rotating anode 6. 1c. The envelope 1 is made of an insulating material such as glass or ceramics. However, since the average temperature of the anode target 7 may exceed 1000 ° C. in the large capacity X-ray tube 101, it is necessary to withstand the radiant heat from the anode target 7. Therefore, the envelope 1 may use metal for a part of the envelope 1 while being insulated from the rotating anode 6 and the cathode 2. In FIG. 2, the large-diameter portion 1a is configured using a metal material such as copper or stainless steel, and a tube radiation window 110 is attached at a position close to the focal point 5 on the anode target 7 on the side surface.

  The tube radiation window 110 is a window for extracting X-rays to the outside, and is made of a material having good X-ray permeability, for example, a material having a low atomic number such as beryllium, and is coupled to the large diameter portion 1a by brazing or welding. ing. The main part of the cathode insulating part 1b is configured by using an insulator such as glass or ceramic, one end is connected to the large diameter part 1a, and the other end is connected to the stem 2c of the cathode 2. The main part of the anode insulating part 1c is also made of an insulating material such as glass or ceramic, one end is connected to the large diameter part 1a, and the other end is connected to the fixed end part 9b of the axle box 9.

  As shown in FIG. 3, the anode target 7 includes a disk body 7a and a cylindrical target cylinder portion 7b protruding from the disk body 7a in the direction opposite to the cathode 2. The disc body 7a has an inclined surface 7c inclined in the opposite direction to the focusing electrode 2a. A focal point 5 is formed on the inclined surface 7c. The rear surface of the anode target 7 (the surface opposite to the surface facing the focusing electrode 2a) is lined with a molybdenum plate, a graphite plate, or the like in order to increase the heat capacity of the anode target 7. Near the center of the disc body 7a, a target fixing hole 7d consisting of a through hole used for fixing to the rotor 12 is provided.

  The quality of the X-ray 4 changes depending on the material of the anode target 7. Usually, in the X-ray tube 101 for medical use, tungsten, molybdenum or the like is used as the anode target 7. This is because the generation efficiency of X-rays 4 increases in proportion to the atomic number of the material of the anode target 7, and it is less than 1% of the collision energy that is converted to X-rays 4 on the collision surface of the electron beam 3. Another reason is that a material having a high melting point is suitable for the anode target 7 because it is converted into heat and raises the temperature of the focal point 5. Therefore, the anode target 7 of the present embodiment is configured using tungsten or a tungsten alloy.

  The rotor 12 includes a small-diameter portion 12a connected to the anode target 7, a large-diameter portion 12b that receives a rotational driving force from a stator coil 21 disposed outside the X-ray tube 101, and the small-diameter portion 12a and the large-diameter A connecting portion 12c that couples the portion 12b.

  The small-diameter portion 12a of the rotor 12 is configured using a metal material having high heat resistance and high strength such as molybdenum.

  The large-diameter portion 12b of the rotor 12 has a cylindrical shape with a hollow portion 12b1 inside, and is configured using a highly conductive metal material such as copper.

  The connecting portion 12c of the rotor 12 includes a cylindrical portion 12c2 having a hollow portion 12c1 communicating with the hollow portion 12b1 in the large diameter portion 12b, and a disk-shaped surface portion 12c3 for sealing the surface of the cylindrical portion 12c2 on the anode target 7 side. Have. The connection portion 12c is configured using a high-strength metal material, and is connected to the small diameter portion 12a and the large diameter portion 12b by brazing or the like.

  The end on the anode side of the small diameter portion 12a is coupled to the vicinity of the center of the surface portion 12c3. In addition, a fastening portion 12a1 having a thread groove is provided at the distal end portion on the cathode 2 side of the small diameter portion 12a. The fastening portion 12a1 passes through the target fixing hole 7d provided in the anode target 7, and fastens the open end (end portion on the cathode 2 side) of the fastening portion 12a1 with a fixture, for example, a nut 201. As a result, the anode target 7 is coupled to the small diameter portion 12a of the rotor 12. In order to avoid loosening of the nut 201 which fixes the anode target 7 and the rotor 12 due to the rotation of the anode 6, the anode target 7, the rotor 12 and the anode rotating shaft 8 are brazed. Alternatively, an integrated target integrated by friction welding or the like may be used.

  The rotor 12 and the anode rotating shaft 8 are coupled at a connection portion 12c of the rotor 12. Between the rotor 12 and the anode rotating shaft 8, a heat insulating portion 202 is inserted and coupled. The heat insulating portion 202 has a thin cylindrical portion and is made of stainless steel having a low thermal conductivity. This heat insulating portion 202 is often applied when the heat capacity of the rotary anode 6 of the X-ray tube is large. In the present embodiment, the rotor 12 and the anode rotating shaft 8 are coupled via the heat insulating portion 202, but the heat insulating portion 202 is not essential, and the rotor 12 and the anode rotating shaft 8 may be directly coupled.

  The rotor 12 generates rotational torque by a stator coil 21 provided outside the X-ray tube 101, but a material having a low electrical resistance such as copper is used in order to efficiently generate eddy current by the stator coil 21. It is preferable. Further, in order to efficiently take in the induced magnetic field from the outside of the X-ray tube 101, the rotor 12 is provided at the outermost edge of the anode (assembly) 6. A cylindrical magnetic part 117 is disposed between the large diameter part 12 b of the rotor 12 and the cylindrical part 9 a of the axle box 9. The magnetic part 117 is for drawing a rotating magnetic field from the stator coil 21, and is made of a ferromagnetic metal material such as iron. The magnetic part 117 is fixed to the cylindrical part 9a or the large-diameter part 12b of the rotor 12. In this embodiment, the magnetic part 117 is fixed to the outer periphery of the cylindrical part 9a.

  The thickness of the magnetic part 117 is about 1 mm (about 0.5 mm to 3 mm). In the rotary anode 6 that employs the axle box 9 made of pure iron, the axle box 9 may also serve as the magnetic part 117 in some cases.

  The anode rotating shaft 8 includes a disk-shaped flange portion 8a coupled to the heat insulating portion 202, and a cylindrical portion 8b whose axial direction extends from the flange portion 8a in the direction opposite to the anode target 7. The flange portion 8a and the cylindrical portion 8b are configured using a high-strength steel material. The flange portion 8a and the connecting portion 12c of the rotor 12 are coupled via the heat insulating portion 202. Then, the anode target 7, the rotor 12, the heat insulating portion 202, and the anode rotating shaft 8 are connected. The anode target 7, the rotor 12, the heat insulating portion 202, and the anode rotating shaft 8 rotate together to form a rotating body. The rotating anode X-ray tube apparatus shown in FIG. 1 is mounted on the gantry of an X-ray CT apparatus, for example, and rotates around the subject by 360 degrees. The relationship of changes at any time, such as vertical, crossing, and parallel.

  The axle box 9 rotatably supports the rotating body, has a sealing surface for sealing one end portion of a substantially cylindrical member, and a cylindrical portion 9a formed by opening the other end portion, and a cylinder A fixed end 9b formed to protrude from the sealing surface of the portion 9a in the opposite direction to the anode target 7, and fixed to the anode support 103 by the anode fixing screw 104 (see FIG. 1), and the outer periphery of the fixed end 9b And a ring portion 9c connected to the anode insulating portion 1c of the envelope 1.

  An anode lead (not shown) of the anode side high-voltage socket 108 (see FIG. 1) is connected to the fixed end portion 9b, and a positive high voltage is supplied through the anode lead. A part of the fixed end 9b is exposed to the outside of the envelope 1 of the X-ray tube 101 and becomes one of the paths for releasing the heat from the rotating anode 6 to the outside. A high rate material such as copper is used. However, when high strength is required, molybdenum is sometimes used because of its heat resistance and relatively high thermal conductivity. Further, in a small X-ray tube 101 with a small calorific value, a pure iron material or the like may be used as the material of the axle box 9.

  The cylindrical portion 9a is formed in a substantially cylindrical shape having an opening 9a1 on the anode target 7 side, a sealing surface portion 9a2 on the end opposite to the anode target 7, and a hollow portion 9a3 inside.

  The cylindrical portion 8b of the anode rotating shaft 8 and the bearing unit 10 are accommodated in the hollow portion 9a3. In the anode rotation shaft 8, the columnar portion 8b is disposed inside the hollow portion 9a3, and the flange portion 8a is disposed so as to protrude from the opening 9a1 of the cylindrical portion 9a toward the anode target 7 side. The flange portion 8a is coupled to the inner surface facing the hollow portion 12b1 in the connection portion 12c of the rotor 12 via the heat insulating portion 202.

On the other hand, the bearing unit 10 is disposed along the axial direction of the cylindrical portion 9a of the axle box 9. As shown in FIG. 5, the bearing unit 10 includes two bearings 13 and 17 and a bearing spacer 20.
A bearing spacer 20 is fixed to the axle box 9. Hereinafter, the fixing position of the bearing spacer 20 on the axle box 9 side is referred to as an axle box fixing position 11, and the position for fixing to the axle box 9 on the bearing spacer 20 side is referred to as a spacer fixing position 11b. The two bearings are arranged with the bearing spacer 20 in between.

  Hereinafter, the bearing relatively close to the opening 9a1 (side relatively close to the anode target 7) is referred to as a first bearing 13, and the first bearing 13 across the axle box fixing position 11 and the spacer fixing position 11b. The bearing on the opposite side, that is, the side relatively close to the fixed end portion 9b is referred to as a second bearing 17. Furthermore, the bearing unit 10 includes a first preload structure that applies a constant pressure preload to the first bearing 13 and a second preload structure that applies a constant pressure preload to the second bearing 17. The first preload structure is arranged between the first bearing 13 and the axle box fixing position 11 and the spacer fixing position 11b, and the second preload structure is composed of the second bearing 17, the axle box fixing position 11 and the spacer fixing position 11b. It is arranged between. Details of the bearing unit 10 will be described later.

  Here, the heat flow path inside the rotary anode 6 will be described with reference to FIG.

  Heat generated from the focal point 5 of the anode target 7 is transmitted to the small diameter portion 12a of the rotor 12 through the disk body 7a. Then, it is transmitted to the heat insulating portion 202 via the small diameter portion 12a and the connecting portion 12c of the rotor 12. Further, the heat is transmitted from the heat insulating portion 202 to the flange portion 8a and the cylindrical portion 8b of the anode rotating shaft 8. The heat flow path is transmitted to the cylindrical portion 9a of the axle box 9 via the first bearing 13, and is also transmitted to the cylindrical portion 9a of the axle box 9 via the second bearing 17.

  Then, the cylindrical portion 9a leads to the fixed end portion 9b. The heat insulating part 202 increases the thermal resistance between the rotor 12 and the anode rotating shaft 8 so that the heat generated in the anode target 7 is not transmitted to the bearings 13 and 17 as much as possible. Although 202 is on the heat flow path, high heat generated at the focal point 5 is transmitted to the first bearing 13 and the second bearing 17. In particular, the first bearing 13 transmits a relatively higher temperature than the second bearing 17. Therefore, the first bearing 13 and the second bearing 17 are required to have heat resistance. Furthermore, the first bearing 13 and the second bearing 17 are also required to have vacuum resistance and conductivity.

  Therefore, the first bearing 13 and the second bearing 17 are made of a high-strength steel material or the like. The first bearing 13 and the second bearing 17 are solid lubricated bearings that use a soft metal such as silver or lead as a lubricant. Details of the solid lubricant will be described later. Further, since the bearing unit 10 used in the X-ray tube 101 is greatly affected by heat, when an inner ring rotating type bearing is used, the integral rotating shaft 8 and the inner ring are integrated. It is desirable to use a rubber bearing. Therefore, also in this embodiment, an integral bearing is used as the bearing unit 10. Hereinafter, the structure of the bearing unit 10 using the integral bearing will be described.

  As shown in FIG. 6 (a), the first bearing 13 is a first inner ring portion comprising a concave bearing curved surface (referred to as a race surface) provided along the outer peripheral surface of the cylindrical portion 8b of the anode rotating shaft 8. 205, a first ball 18 that is a rolling element, and a first outer ring 203 having an outer diameter smaller than the inner diameter of the cylindrical portion 9a and made of an annular member. A race surface of the curved first ball 18 is formed on the inner peripheral surface of the first outer ring 203. Then, as shown in FIG. 6 (b), the cylindrical portion 8b of the anode rotating shaft 8 is disposed in the hollow region of the first outer ring 203, and between the race surface of the first inner ring portion 205 and the race surface of the first outer ring 203. A plurality of first balls 18 are arranged along the circumferential direction.

  The second bearing 17 is configured similarly to the first bearing 13. That is, the second bearing 17 includes a second inner ring portion 206 formed of a race surface provided on the cylindrical portion 8b of the anode rotating shaft 8, a second ball 19 that is a rolling element, and a race surface of the second ball 19. A second outer ring 204 (see FIG. 5).

  Each of the first bearing 13 and the second bearing 17 is opposed to the back surface along the rotational axis direction, that is, closer to the rotating body side of the inner ring or the outer ring than the center-to-center distance between the first ball 18 and the second ball 19. It is arranged so that the distance between contact points (action points) with the race surface is longer. In the first embodiment, the distance between the contact point between the first ball 18 and the first inner ring portion 205 and the contact point between the second ball 19 and the second inner ring portion 206 is the center of the first ball 18 and The first bearing 13 and the second bearing 17 are arranged so as to be longer than the distance between the center of the second ball 19.

  The first ball 18 and the second ball 19 among the surfaces of the first ball 18 and the second ball 19 and the race surfaces of the first outer ring 203, the second outer ring 204, the first inner ring portion 205, and the second inner ring portion 206. A solid lubricant is attached to the transfer surface, which is in the range where the contact is made, with an appropriate film thickness. For example, in the first bearing 13, as shown in FIG. 7, an inner ring transfer surface 307 that is a part of the inner ring race surface 306 of the first inner ring portion 205 and an outer ring that is a part of the outer ring race surface 304 of the first outer ring 203. Solid lubricant adheres to the transfer surface 305. Similarly to the first bearing 13, the second bearing 19 has solid lubricant adhered to the inner ring transfer surface and the outer ring transfer surface. Then, as shown in FIG. 8, when the anode rotation shaft 8 is rotated, the first ball 18 is transferred on the inner ring transfer surface 307 and the outer ring transfer surface 305 along the circumferential direction of the anode rotation shaft 8. Similarly, the second ball 19 is also transferred along the circumferential direction of the anode rotating shaft 8 on the inner ring transfer surface of the second inner ring portion 206 and the outer ring transfer surface of the second outer ring 204.

  As a result, the anode rotation shaft 8, the first outer ring 203, and the second outer ring 204 are lubricated and supported rotatably.

  As the solid lubricant, considering use in a vacuum, a soft metal such as silver or lead or a compound easily cleaved such as molybdenum disulfide is used. A method of coating the rolling surfaces of the first ball 18 and the second ball 19, the first outer ring 203, the first inner ring portion 205 of the second outer ring 204, and the second inner ring portion 206 with a soft metal, which is a solid lubricant. There are several. For example, initially, only the first ball 18 and the second ball 19 are coated with a solid lubricant, and the first outer ring 203, the second outer ring 204, the first inner ring portion 205, the second outer ring 203 are rotated by rotation during the manufacturing process. There is a method of attaching to the contact range (rolling surface) of the first ball 18 and the second ball 19 by rolling onto each race surface of the inner ring portion 206. According to this method, the rolling contact surface is coated with solid lubricant, but the race surface other than the transfer surface among the first outer ring 203, the second outer ring 204, the first inner ring portion 205, and the second inner ring portion 206. Is not coated.

  As described above, the solid lubricant does not adhere to the entire inner race surface and outer race surface, but adheres only to the transfer surface, which is the ball contact range. Therefore, in order to improve the lubrication performance and life, in the solid lubricated bearing, the first ball 18 and the second ball 19, the first outer ring 203, the second outer ring 204, the first inner ring portion 205, the second inner ring portion 206. The position of each rolling surface is stabilized, the first ball 18 is the transfer surface of the first outer ring 203 and the first inner ring portion 205, the second ball 19 is each of the second outer ring 204 and the second inner ring portion 206 It is necessary to keep the transfer surface in a rolling state. Therefore, in the present embodiment, each of the first bearing 13 and the second bearing 17 has a preload structure for applying a preload, and the first ball 18 and the second ball 19 include a first outer ring 203, a second outer ring 204, The first inner ring portion 205 and the second inner ring portion 206 are configured to be transferred on the respective rolling surfaces. Hereinafter, the preload structure will be described.

  The preload structure includes a first preload structure that applies preload to the first bearing 13 and a second preload structure that applies preload to the second bearing 17. The first preload structure includes a first preload spring 14 and a first preloader 207. The second preload structure includes a second preload spring 16 and a second preloader 208.

  In the cylindrical portion 9a of the axle box 9, the first direction is the direction toward the opening 9a1 of the cylindrical portion 9a (the direction toward the anode target 7) along the rotation axis direction with reference to the spacer fixing position 11b of the bearing spacer 20. The preload spring 14, the first preloader 207, and the first bearing 13 are arranged in this order. The second preload spring 16, the second preloader 208, and the second bearing 17 are arranged in this order in the direction toward the fixed end 9b along the rotation axis direction with the spacer fixing position 11b as a reference.

  The spring force of the first preload spring 14 and the second preload spring 16 is configured to be smaller than the load from the rotating body. As a result, each preload amount applied by the first preload spring 14 and the second preload spring 16 is smaller than the weight of the rotating body, so that an overload preload is not applied to the first bearing 13 and the second bearing 17. Composed.

  The first preloader 207 is a spacer disposed between the first preload spring 14 and the first bearing 13, and by applying preload directly from the first preload spring 14 to the first bearing 13, This prevents the first bearing 13 from becoming unstable. The second preloader 208 is a spacer disposed between the second preload spring 16 and the second bearing 17, and by applying preload directly from the second preload spring 16 to the second bearing 17, This prevents the second bearing 17 from becoming unstable.

  As shown in FIG. 9, the first preloader 207 and the bearing spacer 20 include a hollow portion that accommodates the column portion 8b, and are configured as an annular member having an outer diameter that is smaller than the inner diameter of the cylindrical portion 9a of the axle box 9. . Similarly to the first preloader 207, the second preloader 208 is configured as an annular member.

  The bearing spacer 20 includes a fixed portion 20a including a spacer fixing position 11b, a first extension portion 20b extending from the fixed portion 20a toward the first bearing 13, and a second extension extending from the fixed portion 20a toward the second bearing 17. Unit 20c. A groove is formed in the spacer fixing position 11b of the fixing portion 20a by recessing the outer surface of the fixing portion 20a along the circumferential direction. The inner diameter of the fixed portion 20a is configured to be smaller than the inner diameters of the first extension portion 20b and the second extension portion 20c. Therefore, the fixing portion 20a protrudes inward from the first extension portion 20b and the second extension portion 20c.

  The first preloader 207 is in contact with the first outer ring 203 and supports one end (the end on the anode target 7 side) of the first preload spring 14, and the shaft of the bearing spacer 20 from the spring support 207a. A spring holding portion 207b that protrudes toward the center in the direction (spacer fixing position 11b) and restricts vibration in the radial direction (r direction) of the first preload spring 14; The inner diameter of the spring support portion 207a and the inner diameter of the spring restraint portion 207b are substantially equal, and the outer diameter of the spring support portion 207a is larger than the outer diameter of the spring restraint portion 207b, and the outer diameter of the first extension portion 20b of the bearing space 20 The configuration is almost equal. The second preloader 208 has the same configuration as the first preloader 207, and includes a spring support portion 208a and a spring restraint portion 208b (see FIG. 10).

  The first outer ring 203 is formed of an annular member that is thinner than the inner diameter of the cylindrical portion 9a of the axle box 9, and is formed from an annular preloader contact portion 203a that contacts the spring support portion 207a and the preloader contact portion 203a. It has a curved race surface portion 203b that protrudes in the opposite direction to the preloader 207 and has a larger inner diameter than the preloader contact portion 203a. The second outer ring 204 has the same configuration as the first outer ring 203, and includes a preloader contact portion 204a and a race surface portion 204b.

  As shown in FIGS. 9 and 10, the spacer fixing position 11b of the bearing spacer 20 and the axle box fixing position 11 of the axle box 9 are fastened by a fixing member, for example, a screw 11c, and the bearing spacer 20 is fixed to the inner wall surface of the axle box 9. Secure to.

  Further, the first preloader 207 is arranged in contact with the end face of the bearing spacer 20 on the anode target 7 side. The first preload spring 14 is disposed on the inner side of the first extension 20b of the bearing spacer 20 and between the fixed portion 20a of the bearing spacer 20 and the first preloader 207. One end of the first preload spring 14 is an anode in the fixed portion 20a of the bearing spacer 20. The other end is brought into contact with the end surface on the target 7 side, and the other end is brought into contact with the surface facing the fixed end 20a of the first preloader 207. The other end portion of the first preload spring 14 is disposed between the first extension portion 20b of the bearing spacer 20 and the spring restraint portion 207b of the first preloader 207, so that the radial direction of the first preload spring 14 ( (r direction) vibration is regulated. The second preload spring 16 and the second preloader 208 are disposed between the bearing spacer 20 and the second outer ring 204, and have the same configuration as the first preload spring 14 and the first preloader 207.

  The first preload spring 14 and the second preload spring 16 are for applying preload to the first outer ring 203 and the second outer ring 204. When the first outer ring 203 and the second outer ring 204 are directly pressed, When the spring contact area of 203 and the second outer ring 204 is small, the first outer ring 203 and the second outer ring 204 are tilted by the contact with the first preload spring 14 and the second preload spring 16, and the operation of the bearing unit 10 is not performed. There is a possibility to stabilize. For this reason, the first preloader 207 and the second preloader 208 as spacers are inserted between the first preload spring 14 and the first outer ring 203 and between the second preload spring 16 and the second outer ring 204, respectively. The first preloader 207 and the second preloader 208 hold the first preload spring 14 and the second preload spring 16, and prevent contact between the cylindrical portion 8b of the anode rotating shaft 8 and the bearing spacer 20.

  A surface of the spring support portion 207a of the first preloader 207 facing the first outer ring 203 is in contact with the preloader contact portion 203a of the first outer ring 203. When the first preloader 207 is pressed against the first outer ring 203 by the spring force of the first preload spring 14, between the first extension 20b of the bearing spacer 20 and the spring support 207a of the first preloader 207, An axial gap 401-1 is formed. The spring holding portion 207b is located closer to the cylindrical portion 8b side of the anode rotation shaft 8 than the first preload spring 14, and restricts the swing width when the first preload spring 14 vibrates in the radial direction during rotation.

  The second preload spring 16 is arranged with one end contacting the spring support portion 208a of the second preloader 208 and the other end contacting the fixing portion 20a of the bearing spacer 20. A surface of the spring support portion 208a of the second preloader 208 facing the second outer ring 204 is in contact with the preloader contact portion 204a of the second outer ring 204. The second preloader 208 is pressed against the second outer ring 204 by the spring force of the second preload spring 16, so that the second extension 20 c of the bearing spacer 20 and the spring support 208 a of the second preloader 208 are interposed. An axial gap 401-2 is formed. The spring holding portion 208b is located on the inner side of the second preload spring 16, and regulates the swing width when the second preload spring 16 vibrates in the radial direction during rotation.

  The gap width of the axial gaps 401-1 and 401-2 is adjusted according to the length of the bearing spacer 20, but the length of the bearing spacer 20 in the rotation axis direction can be adjusted even when the bearing spacer 20 is thermally expanded. 401-1 and 401-2 are formed with dimensions that can be secured. However, if the axial gaps 401-1 and 401-2 are too large, the bearing unit 10 performs an unstable operation. Therefore, the gap width is preferably about several to several tens of μm.

As described above, since the first bearing 13 and the second bearing 17 are used in a high temperature environment, the first preload spring 14 and the second preload spring 16 for applying preload also need to have high temperature resistance. . In particular, when the elastic modulus of the spring is reduced (sagging) in a high temperature environment, not only vibration and noise increase, but also the lubrication performance itself decreases. For this reason, a material having a tensile strength of about 100 kgf / mm ^{2 in the} operating temperature range is optimal for the spring material based on the fatigue strength data of the spring specified in JIS B 2704. Examples of such a spring material include incoloy, inconel, and hastelloy.

  Note that the preload spring is not necessarily composed of a single spring, but a large-diameter coil spring and a small-diameter coil spring using a thin linear coil spring are formed, and the small-diameter coil spring is included in the large-diameter coil spring, and the coil spring is doubled. By installing, it is also possible to reduce the installation location of the preload structural component. In particular, as in this embodiment, when a preload spring is installed inside the rotating anode of the X-ray tube apparatus, it is effective because the installation space for the preload spring is limited in consideration of the surrounding electric field. Further, when the length direction of the spring is limited, a wave spring may be employed.

  The effect of this embodiment is demonstrated using a comparative example.

  First, as a first comparative example, the behavior of a bearing having no preload and no axial gap will be described with reference to FIG. FIG. 11 is an explanatory view of an axial section of a bearing unit without preload and without an axial gap, and the direction in which the anode rotation shaft 7 is located is directed downward in the gravity direction, and the rotation axis direction is parallel to the gravity direction. It shows from the rotation center axis to the outer edge in the state of being made.

  The bearing unit 85 of FIG. 11 includes a first inner ring portion 205, a first outer ring 203, a first ball 18, a second inner ring portion 206, a second outer ring 204, a second ball 19, and a bearing spacer 83. The bearing spacer 83 is fixed to the axle box fixing position 11 of the axle box 9. The bearing spacer 83 is brought into contact with the first outer ring 203 and the second outer ring 204, and the bearing spacer 83 supports the load of the rotating body via the second outer ring 204 and the second ball 19.

  In the bearing unit 85 of FIG. 11, the first inner ring portion 205, the first outer ring 203, the first ball 18, the second inner ring portion 206, the second outer ring 204, the second ball 19, and the bearing spacer 83 are always in contact. For this reason, there is a problem that when rotating in this state, the amount of wear is large, and there is a possibility that the service life may be shortened.

  Next, as a second comparative example, the behavior of the bearing unit in which an axial gap is provided between the outer ring and the bearing spacer in order to reduce the amount of wear and no preload is applied will be described with reference to FIGS. To do. FIG. 12 is an axial sectional view of a bearing unit without preload and having an axial gap (however, it shows from the rotation center axis to the outer edge). FIG. 13 is an explanatory view showing the behavior of a bearing unit without preload and having an axial gap, where (a) shows a state where a load in the axial direction (rotational axis direction) is applied and the first outer ring 203 falls. (B) shows a state where the axial load is applied but the first outer ring 203 cannot fall.

  12 includes a first inner ring portion 205, a first outer ring 203, a first ball 18, a second inner ring portion 206, a second outer ring 204, a second ball 19, and a bearing spacer 84. The bearing spacer 84 is fixed to the axle box fixing position 11 of the axle box 9. The axial dimension of the bearing spacer 84 in the rotation axis direction is made shorter than that in the first comparative example, so that the axial gap 89-1 is between the bearing spacer 84 and the first outer ring 203, and between the bearing spacer 84 and the second outer ring 204. An axial gap 89-2 is formed.

  In a state where the rotation axis direction coincides with the horizontal direction, a load in the axial direction (rotation axis direction) is not applied and the bearing is in a neutral position. At this time, as shown in FIG. 12, the first inner ring portion 205, the first ball 18, and the first outer ring 203 are in contact with each other, the second inner ring portion 206, the second ball 19, and the second outer ring 204 are in contact with each other, Axial gaps 89-1 and 89-2 are formed between the bearing spacer 84 and the first outer ring 203 and the second outer ring 204, respectively.

  When the rotation axis direction does not coincide with the horizontal direction, an axial load is applied to the bearing unit 86. The state of the components of the bearing unit 86 at this time will be described. In FIG. 13, the case where the axial direction coincides with the gravity direction, that is, the case where the axial load applied to the bearing located on the upper side in the gravity direction is maximized is illustrated as an example.

  As shown in FIG. 13 (a), the cylindrical portion 8b of the anode rotation shaft 8 falls (moves) along the direction of gravity, and the second inner ring portion 206 integrated therewith contacts the second ball 19 ( 13), the second ball 19 is pressed against the second outer ring 204 (circle 2 in FIG. 13), the second outer ring 204 contacts the bearing spacer 84 fixed to the axle box 9, and the bearing spacer 84 Supported (circle 3 in FIG. 13).

  On the other hand, the first outer ring 203 falls (moves) in the direction of gravity by its own weight and comes into contact with the first ball 18, and the first outer ring 203 applies a load equivalent to its own weight to the first ball 18 (circle 4 in FIG. 13), The first ball 18 is pressed against the first inner ring portion 205 with a force corresponding to the weight of the first outer ring 204 and the first ball 18 (circle 5 in FIG. 13). At this time, the axial gap 89-2 becomes 0 when the bearing spacer 84 and the second outer ring 204 are in contact with each other, and the axial gap 89-1 has a gap width of the state shown in FIG. This is wider than the state when the rotation axis direction coincides with the horizontal direction. The total load of the rotating body is supported by the bearing spacer 84 via the second inner ring portion 206, the second ball 19, and the second outer ring 204.

  However, as shown in FIG. 13 (b), when the first outer ring 203 does not fall due to friction with the inner wall surface of the axle box 9 (circle 4 ′ in FIG. 13), the axial gap 89-1 is as shown in FIG. In this state, the first ball 18 and the first outer ring 203 are not in contact with each other, and there is nothing to suppress the first ball 18, so that the first ball 18 can move freely.

  As described above, in the solid lubricated bearing, the range where the lubricant adheres is limited to the contact range (ball rolling surface) with which the ball contacts among the bearing curved surfaces of the inner ring and the outer ring. As shown in Fig. 4, when the ball is allowed to move freely, there is a possibility that the ball may come into contact with the bearing curved surface having no solid lubricant on the inner ring and the outer ring, and the bearing curved surface may be worn out. is there.

As a third comparative example, an example in which an axial gap and a preload structure are provided only on one of two bearings arranged in the rotation axis direction will be described. The axial gap and the preload structure are provided in the bearing located on the upper side along the direction of gravity when the axial direction of the rotation coincides with the direction of gravity and an axial load is applied to the bearing. Hereinafter, a third comparative example will be described with reference to FIG.
FIG. 14 is an explanatory view showing the behavior of a bearing unit having a preload structure and an axial gap only in a bearing located on the upper side in the direction of gravity.

  The bearing unit 87 shown in FIG. 14 includes a preload spring 90 and a preloader 91 between the second outer ring 204 and the bearing spacer 88. The axial dimension of the bearing spacer 88 is formed such that an axial gap 92 is formed between the second outer ring 204 and the first outer ring 203 and the bearing spacer 88 are in contact with each other. The bearing spacer 88 is fixed to the axle box fixing position 11 of the axle box 9.

  When an axial load is applied to the bearing unit 87, the second inner ring portion 206 comes into contact with the second ball 19, and the entire load of the rotating body is applied to the second ball 19 (circle 1 in FIG. 14). The second ball 19 and the second outer ring 204 come into contact with each other, and the total load of the rotating body and the weight of the second ball 19 are transmitted from the second ball 19 to the second outer ring 204 (circle 2 in FIG. 14). The second outer ring 204 is supported by the preload spring 90 via the preloader 91 (circle 3 in FIG. 14).

  On the other hand, the first outer ring 203 comes into contact with the first ball 18, and the weight of the first outer ring 203 is applied to the first ball 18 (circle 4 in FIG. 14). The first ball 18 also contacts the first inner ring portion 205, and the weights of the first outer ring 203 and the first ball 18 are applied to the first inner ring portion 205 (circle 5 in FIG. 14). If the spring force of the preload spring 90 applies a force larger than the total load of the rotating body by the weight of the first ball 18, the second ball 19, the first outer ring 203, and the second outer ring 204, The one outer ring 203 and the first ball 18 are moved upward along the direction of gravity by the preload spring 90 via the cylindrical portion 8b of the anode rotation shaft 8, the second ball 19 and the second outer ring 204 (on the paper surface of FIG. 14). (Upward).

  The first inner ring portion 205, the first ball 18, the first outer ring 203, the second inner ring portion 206, the second ball 19, and the second outer ring 204 are always kept in contact with each other by the balance of these forces. Unlike the state of the axial gap = 0 shown in FIG. 5, the preload spring 90 absorbs the displacement caused by thermal expansion and vibration of the bearing components, so that the lubrication performance is not adversely affected.

  Further, unlike the structure of the second comparative example having an axial gap and no preload, the ball of the bearing located on the load side does not move freely.

  However, in the case of the third comparative example, the spring force of the preload spring needs to be sufficiently larger than the applied load in order to maintain the contact between the ball positioned on the lower side in the axial direction and the transfer surface. Such a spring force is such that even if the rotation center axis of the anode rotation shaft 8 coincides with the horizontal direction and the load in the axial direction (axial direction) is almost zero, the first inner ring portion 205 and the second inner ring portion 206, the first outer ring 203, and the second outer ring 204 are burdened. In contrast, in the preload structure of the bearing unit according to the present embodiment, the amount of preload can be reduced as compared with the third comparative example, and the first inner ring portion 205, the second inner ring portion 206, the first outer ring 203, and the second outer ring. The burden on 204 can be reduced. Details thereof will be described below.

  The behavior of the bearing unit 10 of the present embodiment when no axial load is applied and the behavior when the axial load is applied will be described with reference to FIGS. 15 and 16. FIG. 15 is an explanatory diagram showing a behavior when an axial load is not applied to the bearing unit 10 according to the present embodiment. FIG. 16 is an explanatory diagram showing the behavior when an axial load is applied to the bearing unit 10 according to the present embodiment.

  When the axial load is 0, that is, when the rotation axis direction coincides with the horizontal direction, the second preload spring 16 pushes the second outer ring 204 via the second preloader 208 as shown in FIG. (Circle 1 in Figure 15). As a result, the second outer ring 204 contacts the second ball 19 (circle 2 in FIG. 15), the second ball 19 contacts the second inner ring portion 206 (circle 3 in FIG. 15), and the components of the second bearing 17 However, the contact state at a certain position is maintained. The first preload spring 14 pushes the first outer ring 203 via the first preloader 207 (circle 4 in FIG. 15), so that the first outer ring 203 contacts the first ball 18 (circle 5 in FIG. 15). ), The first ball 18 comes into contact with the first inner ring portion 205 (circle 6 in FIG. 15), and the components of the first bearing 13 are kept in contact at a certain position.

  When the rotary anode is tilted and the rotation axis direction does not coincide with the horizontal direction, and the load in the axial direction (arrow Ax direction) is applied to the second bearing 17, as shown in FIG. 16, it is integrated with the anode rotation axis 8. The second inner ring portion 206 is pulled in the load direction, whereby the second ball 19 is pressed downward (circle 1 in FIG. 16). The second outer ring 204 is pressed by the second ball 19 pressed downward (circle 2 in FIG. 16), and the second outer ring 204 pushes down the second preloader 208 (circle 3 in FIG. 16). At this time, the second preload spring 16 contracts and the second preloader 208 is pushed down, the second preloader 208 contacts the second extension 20c of the bearing spacer 20, and the axial gap 401-2 has a gap width = 0. It becomes.

  On the other hand, in the first bearing 13, the first preload spring 14 pushes down the first preloader 207 in the load direction (downward in FIG. 16), and the first preloader 207 is pressed against the first outer ring 203 (see FIG. 16 circles 4). Then, the first outer ring 203 pushes down the first ball 18 (circle 5 in FIG. 16), and the first ball 18 comes into contact with the first inner ring portion 205 (circle 6 in FIG. 16). At this time, the axial gap 401-1 is wider than the gap width of the axial gap 401-1 in FIG. 15 by the amount corresponding to the drop width of the first preload spring 14, the first preloader 207, and the first outer ring 203. As described above, the positional relationship of the components of the first bearing 13 is the same as in the case where the axial load in FIG. 15 is not applied. The state of rolling on the transfer surface of the first outer ring 203 can be maintained.

  According to the present embodiment, the first bearing 13 and the second bearing 17 can be held in place regardless of whether or not an axial load is applied. Thereby, the first ball 18 and the second ball 19 roll on the transfer surface to which the fixed lubricant is applied, and the rotational performance of the first bearing 13 and the second bearing 17 can be maintained. Further, since the preload structure applies preload using the spring force of the first preload spring 14 and the second preload spring 16, there is a phenomenon such as insufficient preload due to heat transfer delay, which is seen in the preload structure using heat. Never happen.

Further, according to the present embodiment, the spring force with respect to each of the first bearing 13 and the second bearing 17 may be smaller than the rotating body load applied to each of the first bearing 13 and the second bearing 17.
Therefore, it is possible to allow the ball position to be stabilized and operated after the familiar operation is finally completed while allowing a certain amount of play in the ball position during the initial familiar operation. In addition, the lubrication performance of the bearing can be improved by making it possible to adjust the spring load in a small range without being limited by the rotating body load.

  Furthermore, since the anode rotating shaft 8 has a higher temperature than the first outer ring 203 and the second outer ring 204, when a separate inner ring member is fixed to the anode rotating shaft 8, the anode rotating shaft 8 is thermally expanded. However, according to this embodiment, the first inner ring portion 205 and the second inner ring portion 206 are formed integrally with the anode rotating shaft 8 to eliminate the above-mentioned concerns. It becomes possible to do.

<Second embodiment>
The second embodiment has a tube structure in which the outer ring rotates to rotate the anode target. Hereinafter, the second embodiment will be described with reference to FIGS. FIG. 17 is an axial sectional view showing a schematic configuration of the X-ray tube according to the second embodiment. FIG. 18 is a cross-sectional view in the axial direction showing the schematic configuration of the rotating anode (however, from the rotation center axis to the outer edge). FIG. 19 is a cross-sectional view in the axial direction of the bearing unit 10 employing the preload structure bearing according to the second embodiment (however, from the rotation center axis to the outer edge). FIG. 20 is an explanatory diagram showing the behavior of the bearing unit when no axial load is applied to the bearing unit according to the second embodiment. FIG. 21 is an explanatory view showing the behavior of the bearing unit when an axial load is applied to the bearing unit according to the second embodiment. Note that, through FIGS. 17 to 21, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  The X-ray tube according to the second embodiment shown in FIG. 17 is configured to be included in the cathode 2 and the rotary anode 6 'envelope 1. The rotating anode 6 ′ includes an anode target 7, a rotor 12, a shaft box 9 ′, a bearing unit 10 ′, a heat insulating portion 202 ′, and a fixed shaft 502. Inside the axle box 9 ′, there is a bearing unit 10 ′ that rotatably supports the axle box 9 ′, and a cylindrical portion that is fixed to the anode side support of the X-ray tube. And a fixed shaft 502 that supports the shaft box 9 ′. That is, the fixed shaft 502 forms a fixed body.

  On the other hand, the heat insulating portion 202 'connects the rotor 12 and the axle box 9', and the anode target 7, the rotor 12, the heat insulating portion 202 'and the axle box 9' rotate. That is, the anode target 7, the rotor 12, the heat insulating portion 202 'and the shaft box 9' form a rotating body and are rotatably supported by the fixed shaft 502 via the bearing unit 10 '.

  As shown in FIG. 18, in the bearing unit 10 ′, the first bearing 13 ′ and the second bearing 17 ′ are arranged on both sides of the axle box fixing position 11. The first bearing 13 ′ includes a first inner ring 205 ′ that is configured separately from the fixed shaft 502, a first ball 18, and a first outer ring 203. Similarly, the second bearing 17 ′ includes a second inner ring 206 ′ configured separately from the fixed shaft 502, a second ball 19, and a second outer ring 204.

  A first bearing 13 ′, a second bearing 17 ′, an inner diameter side spacer 504, an outer diameter side spacer 503, a first preload spring 14, and a second preload spring 16 are provided in the shaft box 9 ′.

  The outer diameter side spacer 503 is fastened by a fixing member, for example, a screw, between the first outer ring 203 and the second outer ring 204 and at the axle box fixing position 11 of the axle box 9 '. By disposing the outer diameter side spacer 503 between the first outer ring 203 and the second outer ring 204, the first outer ring 203 and the second outer ring 204 are arranged at a constant interval. Further, the end of the first outer ring 203 on the anode target 7 side is fixed to the axle box 9 ′ by a bearing pressing screw 501.

  The inner diameter side spacer 504 is fixed between the first inner ring 205 ′ and the second inner ring 206 ′ and on the outer surface of the fixed shaft 502. Further, the end of the axle box 9 'opposite to the anode target 7 forms a projection 9d having a smaller inner diameter than the other regions. Then, one end of the second outer ring 204 is in contact with the protrusion 9d, and the other end is in contact with the outer diameter side spacer 503, thereby holding the position of the second outer ring 204. As shown in FIG. 19, the inner diameter side spacer 504 is fastened to a middle position between the first inner ring 205 ′ and the second inner ring 206 ′ on the fixed shaft 502 by a fixing member, for example, an inner diameter side spacer fixing screw 505.

  A first preload spring 14 and a first preloader 207 are disposed between the first inner ring 205 ′ and the inner diameter side spacer 504. One end of the first preload spring 14 is in contact with the inner diameter side spacer 504, and the other end is in contact with the first preloader 207.

  A second preload spring 16 and a second preloader 208 are arranged between the second inner ring 206 ′ and the inner diameter side spacer 504. One end of the second preload spring 16 is in contact with the inner diameter side spacer 504, and the other end is in contact with the second preloader 208.

  The first preload spring 14 and the first preloader 207 apply preload to the first bearing 13 ′, and the second preload spring 16 and the second preloader 208 apply preload to the second bearing 17 ′. A preload is applied to each bearing.

  FIG. 20 shows a state where an axial load is not applied to the axle box 9 ', and FIG. 21 shows a state where a load is applied.

  As shown in FIG. 20, when the load is 0, the second inner ring 206 ′ of the second bearing 17 ′ is pushed up by the second preload spring 16 via the second preloader 208 (circle 1 in FIG. 20). Thus, the second inner ring 206 ′ contacts the second ball 19 (circle 2 in FIG. 20), the second ball 19 contacts the second outer ring 204 (circle 3 in FIG. 20), and the second bearing 17 The components are kept in contact at a certain position. At this time, an axial gap 401-2 ′ is formed between the inner diameter side spacer 504 and the second preloader 208.

  On the other hand, the first preload spring 14 pushes down the first inner ring 205 ′ via the first preloader 207 (circle 4 in FIG. 20), whereby the first inner ring 205 ′ contacts the first ball 18 (FIG. 20), the first ball 18 comes into contact with the first outer ring 203 (circle 6 in FIG. 20), and the components of the first bearing 13 ′ are kept in contact at a certain position. At this time, an axial gap 401-1 'is formed between the inner diameter side spacer 504 and the first preloader 207.

  From this state, when an axial load is applied in the direction of the arrow Ax in FIG. 21, the axle box 9 'moves in the load direction, and the second outer ring 204 moves in the load direction together with the axle box 9'. As a result, the second ball 19 is pushed down (circle 1 in FIG. 21), and the second ball 19 pushes down the second inner ring 206 ′ (circle 2 in FIG. 21), but the second preload spring 16 contracts. Thus, the second inner ring 206 ′ is supported by the inner diameter side spacer 504 via the second preloader 208 and the second preload spring 16 (circle 3 in FIG. 21). At this time, the axial gap width of the axial gap 401-2 'becomes zero due to the contact between the second preloader 208 and the inner diameter side spacer 504.

  On the other hand, in the first bearing 13 ′, the axle box 9 ′ moves in the load direction, but the first preload spring 14 pushes down the first preloader 207 in the load direction (downward in FIG. 21), and the first preloader 207 is pressed against the first inner ring 205 (circle 4 in FIG. 21). Then, the first inner ring 205 ′ pushes down the first ball 18 (circle 5 in FIG. 21), and the state where the first ball 18 is in contact with the first outer ring 203 (circle 6 in FIG. 21) is maintained. As a result, the positional relationship of the components of the first bearing 13 ′ is the same as when the load in FIG. 20 is not applied, in which the first ball 18 in the first bearing 13 ′ and the transfer surface of the first inner ring 205 ′ and The state of rolling on the transfer surface of the first outer ring 203 can be maintained. At this time, since the first preload spring 14 is extended and the first preloader 207 is pushed down, the gap width of the axial gap 401-1 'is wider than the state of FIG.

  As described above, according to the present embodiment, the first inner ring 205 ′, the second inner ring 206 ′, the first ball 18, the second ball 19, the first outer ring 203, and the second outer ring 204 regardless of the presence or absence of a load. It is possible to keep the contact state constant, and it is possible to realize stable bearing rotation.

  In the present embodiment, it is difficult to process the bearing race surface directly inside the axle box 9 '. Therefore, the rotating body portion of the bearing unit 10 ′ is configured by assembling the axle box 9 ′, the first outer ring 203 and the second outer ring 204, the outer diameter side spacer 503, and the bearing holding screw 501. In this case, it is desirable that all parts are made of the same material so that thermal stress is not generated between the parts due to thermal expansion. However, since this structure also causes a gap during assembly, the structure in which the anode rotation shaft rotates in the first embodiment can directly process the bearing inner ring on the anode rotation shaft. There are advantages. In the above embodiment, a bearing having two bearings is taken as an example. However, three or more bearings are provided along the rotation axis direction, and each bearing has a maximum axial load applied to each bearing. A preload structure that provides a small amount of preload may be provided.

<Third embodiment>
The rotary anode X-ray tube according to each of the above embodiments may be used in an X-ray imaging apparatus. As an example of an X-ray imaging apparatus, in the present embodiment, an X-ray CT apparatus will be described as an example. However, an X-ray imaging apparatus that can perform fluoroscopy and imaging, a movable type or a ceiling or the like is fixed. The rotating anode X-ray tube according to the above embodiment can be applied to any X-ray imaging apparatus that images an object using X-rays, such as an X-ray imaging apparatus that captures images. FIG. 22 is a functional block diagram showing the overall configuration of the X-ray CT apparatus using the rotary anode X-ray tube according to the embodiment.

The X-ray CT apparatus 600 in FIG. 22 includes a scan gantry unit 611 and a console 620.
The scan gantry unit 611 includes a rotary anode X-ray tube device 601, a rotary disk 602, a collimator unit 603, an X-ray detector 606, a data collection device 607, a bed 605, and a gantry control according to the above embodiment. A device 608, a bed control device 609, and an X-ray control device 610 are provided.

  The X-ray control device 610 performs control necessary for X-ray generation, such as applying a high voltage to the rotary anode X-ray tube device 601. The collimator unit 603 includes a mechanism for limiting the X-ray irradiation range irradiated from the rotary anode X-ray tube device 601 and an X-ray compensator for adjusting the X-ray dose distribution.

  The rotating disk 602 includes an opening 604 into which a subject placed on a bed 605 enters, and a rotating anode type X-ray tube device 601 and an X-ray detector 606 are mounted to rotate around the subject. It is.

  The X-ray detector 606 is a device that measures the spatial distribution of transmitted X-rays by detecting X-rays that have passed through the subject, and is disposed opposite to the rotary anode X-ray tube device 601. The line detection elements are arranged in the rotation direction of the rotating disk 602, or are arranged two-dimensionally in the rotation direction (channel direction) of the rotating disk 602 and the rotation axis direction (slice direction). Each X-ray detection element detects X-rays transmitted through the subject and outputs analog data corresponding to the transmitted X-ray dose.

  The data collection device 607 is a device that converts analog data output from the X-ray detector 606 into digital data and collects it.

  The gantry control device 608 is a device that controls the rotation of the rotary disk 602. The bed control device 609 is a device that controls the vertical movement of the bed 605.

  The console 620 includes an input device 621, an image arithmetic device 622, a display device 625, a storage device 623, and a system control device 624.

  The input device 621 is a device for inputting a subject's name, examination date and time, imaging conditions, and the like, specifically a keyboard or a pointing device. The image computation device 622 is a device that uses the digital data sent from the data collection device 607 as measurement data and performs a reconstruction computation process based on this data to generate a CT image. The display device 625 is a device that displays the CT image reconstructed by the image calculation device 622, and specifically, is a CRT (Cathode-Ray Tube), a liquid crystal display, or the like. The storage device 623 is a device that stores measurement data collected by the data collection device 607 and image data of a CT image created by the image calculation device 622, and is specifically an HDD (Hard Disk Drive) or the like. The system control device 624 controls these devices, the gantry control device 608, the bed control device 609, and the X-ray control device 610.

  The X-ray control device 610 controls the electric power input to the rotary anode type X-ray tube device 601 based on the imaging conditions input from the input device 621, particularly the X-ray tube voltage and X-ray tube current. The model X-ray tube apparatus 601 irradiates a subject with X-rays according to imaging conditions. The X-ray detector 606 detects X-rays irradiated from the rotary anode X-ray tube device 601 and transmitted through the subject with a large number of X-ray detection elements, and measures the distribution of transmitted X-rays. The rotating disk 602 is controlled by the gantry control device 608 and rotates based on the photographing conditions input from the input device 621, particularly the rotation speed. As the rotary disk 602 rotates, the rotation axis direction of the rotary anode 6 in the rotary anode X-ray tube device 601 changes from the vertical direction (gravity direction) to the horizontal direction and the anti-vertical direction (antigravity direction). The couch 605 is controlled by the couch controller 609 and operates based on the imaging conditions input from the input device 621, particularly the helical pitch.

  1 Envelope, 2 Cathode, 2a Focusing electrode, 2b Holder, 2c Stem, 3 Electron, 4 X-ray, 5 Focus (electron collision range), 6 Rotating anode (assembly), 7 Anode target, 7a Disc body, 7b Cylindrical part, 7c inclined surface part, 7d target fixing hole, 8 anode rotating shaft, 8a flange part, 8b cylindrical part, 9-axis box, 9'-axis box, 9a cylindrical part, 9a1 opening part, 9a2 bottom part, 9a3 hollow part, 9b Fixed end, 9c ring, 9d protrusion, 10 bearing unit, 10 'bearing unit, 11 axle box fixing position, 11b spacer fixing position, 11c screw, 12 rotor, 12a narrow diameter part, 12a1 fastening part, 12b large diameter Part, 12b1 hollow part, 12c connecting part, 12c1 hollow part, 12c2 cylindrical part, 12c3 face part, 13 first bearing, 13 'first bearing, 14 first preload spring, 16 second preload spring, 17 second bearing, 17 'second bearing, 18 first ball, 19 second ball, 20 bearing spacer, 20a fixed part, 20b first extension part, 20c Second extension, 21 Stator coil, 83, 84, 88 Bearing spacer, 85, 86, 87 Bearing unit, 89-1, 89-2, 92 Axial clearance, 90 Preload spring, 91 Preloader, 101 X-ray tube , 102 Tube container, 103 Anode support, 104 Anode fixing screw, 105 Tube container radiation window, 106 Cathode support, 107 High voltage socket (-side), 108 High voltage socket (+ side), 109 Insulating oil, 110 tube Spherical radiation window, 117 magnetic part, 201 nut, 202 heat insulation part, 202 'heat insulation part, 203 first outer ring, 203a preloader contact part, 203b race surface part, 204 second outer ring, 204a preloader contact part, 204b race Face part, 205 First inner ring part, 205 ′ First inner ring, 206 Second inner ring part, 206 ′ Second inner ring, 207 First preloader, 207a Spring support part, 207b Spring holding part, 208 Second preloader, 208a Spring Support part, 208b Spring restraint part, 304 outer ring race surface (bearing curved surface), 305 outer ring transfer surface (ball contact range in race surface), 306 inside Wheel race surface (bearing curved surface), 307 Inner ring transfer surface (ball contact range in race surface), 401-1 axial clearance, 401-1 'axial clearance, 401-2 axial clearance, 401-2' axial clearance, 501 bearing Presser screw, 502 fixed shaft, 503 outer diameter side spacer, 504 inner diameter side spacer, 505 inner diameter side spacer fixing screw, 600 X-ray CT device, 601 rotating anode type X-ray tube device, 602 rotating disk, 603 collimator unit, 604 opening 605 bed, 606 X-ray detector, 607 data acquisition device fixed shaft, 608 gantry control device, 609 bed control device, 610 X-ray control device, 611 bearing cap screw, 620 console, 621 input device, 622 image calculation Device, 623 storage device, 624 system control device, 625 display device

Claims (14)

A cathode that generates an electron beam;
A rotating anode including an anode target that collides with the electron beam to generate X-rays;
A rotary anode X-ray tube device comprising:
The rotating anode includes a rotating body that rotates together with the anode target, a bearing unit that lubricates rotation of the rotating body, a fixed body that rotatably supports the rotating body via the bearing unit, With
The bearing unit includes a plurality of bearings arranged along the axial direction of the rotating body, and a preload structure provided one for each bearing,
Each of the preload structures provides the bearing with a preload amount smaller than a load applied to the bearing from the rotating body in a state where the rotation axis direction of the rotating body coincides with the direction of gravity. Give,
Rotating anode type X-ray tube device. Each of the bearings has a ball as a rolling element, an inner ring having a bearing curved surface including a contact surface of the ball, and a contact surface with the ball that is located on the opposite side of the inner ring with the ball interposed therebetween. An outer ring, and
The preload structure includes a preload spring that generates preload, and a preloader disposed between the preload spring and the bearing, and the preload spring applies preload to the bearing via the preloader. To
2. The rotary anode type X-ray tube apparatus according to claim 1, wherein The bearing unit further includes a bearing spacer disposed between two adjacent bearings, the bearing spacer is fixed to the fixed body, one end of the preload spring is supported by the bearing spacer, and the other end The part abuts on the preloader,
3. The rotary anode type X-ray tube apparatus according to claim 2, wherein An axial gap is formed between the bearing spacer and the preloader along the rotation axis direction,
The preloader included in the preload structure for the bearing located on the upper side along the gravitational direction in a state in which the rotary anode is in a direction in which the rotation axis direction coincides with the gravitational direction is the bearing spacer The gap width of the axial gap is 0,
The axial gap is provided between the preloader and the bearing spacer included in the preload structure for each of the bearings in a state in which the rotary anode is in a direction in which the rotation axis direction coincides with the horizontal direction. Is formed,
4. The rotary anode type X-ray tube apparatus according to claim 3, wherein The rotating anode further comprises an anode rotating shaft connected to the anode target, and a shaft box that houses the anode rotating shaft and the bearing unit,
The rotating body includes the anode target and the anode rotating shaft,
The fixed body includes the axle box,
5. The rotary anode type X-ray tube apparatus according to claim 4, wherein The bearing spacer is fixed between the inner wall surfaces of the axle box and disposed between two outer rings included in adjacent bearings,
The preloader is disposed between the outer ring and the bearing spacer of each bearing, and the preload spring has one end abutting on the bearing spacer and the other end abutting on each preloader. ,
The axial gap is formed between the bearing spacer and each preloader.
6. The rotary anode type X-ray tube apparatus according to claim 5, wherein The inner ring of each of the bearings is formed integrally with the anode rotation shaft.
6. The rotary anode type X-ray tube apparatus according to claim 5, wherein The rotating anode further includes a shaft box connected to the anode target, and a fixed shaft that rotatably supports the shaft box via the bearing unit,
The axle box houses the bearing unit and the fixed shaft,
The rotating body includes the anode target and the axle box,
The fixed body includes the fixed shaft,
5. The rotary anode type X-ray tube apparatus according to claim 4, wherein The bearing unit is relatively outer along the radial direction of the fixed shaft and relatively outer along the radial direction of the fixed shaft and an outer diameter side spacer disposed between the outer rings of the adjacent bearings. An inner diameter side spacer disposed on the inner side and between the inner rings of the adjacent bearings,
The outer diameter side spacer is fixed to the inner wall surface of the axle box and abuts against the two outer rings included in the adjacent bearings,
The inner diameter side spacer is fixed to the outer surface of the fixed shaft,
The preloader is disposed between the inner ring and the inner diameter side spacer of each of the bearings,
The preload spring has one end abutting on the inner diameter side spacer and the other end abutting on the respective preloader,
The axial gap is formed between the inner diameter side spacer and each of the preloaders.
9. The rotary anode type X-ray tube apparatus according to claim 8, wherein As the preload spring, a double coil spring in which a small diameter coil spring having a relatively small diameter is arranged in a large diameter coil spring having a relatively large diameter,
3. The rotary anode type X-ray tube apparatus according to claim 2, wherein The bearing unit has two bearings that are paired to face each other along a rotation axis direction, and a bearing curved surface of the inner ring or the outer ring that is positioned closer to the rotating body than a distance between centers of the balls of the two bearings. Arranged so that the distance between the contact points of the ball and the ball is longer,
3. The rotary anode type X-ray tube apparatus according to claim 2, wherein Each of the bearings is formed using a solid lubricant.
2. The rotary anode type X-ray tube apparatus according to claim 1, wherein A cathode that generates an electron beam;
A rotating anode including an anode target that collides with the electron beam to generate X-rays;
A rotary anode X-ray tube device comprising:
The rotating anode includes a rotating body that rotates together with the anode target, a bearing unit that lubricates rotation of the rotating body, a fixed body that rotatably supports the rotating body via the bearing unit, With
The bearing unit is disposed between a plurality of bearings disposed along the axial direction of the rotating body, a preload structure provided for each of the bearings, and the plurality of adjacent bearings. Bearing spacers,
Each of the bearings includes a ball serving as a rolling element, an inner ring having a bearing curved surface including a contact surface of the ball, and a contact surface with the ball that is located on the opposite side of the inner ring with the ball interposed therebetween. An outer ring having a curved bearing surface,
Each of the preload structures includes a preload spring that generates a preload, and a preloader including a spacer disposed between the preload spring and the bearing,
The bearing spacer is fixed to the fixed body, one end of the preload spring is supported by the bearing spacer, and the other end abuts the preloader,
An axial gap is formed along the rotation axis direction between the bearing spacer and the preloader. The length of the bearing spacer in the rotation axis direction is such that the bearing spacer is thermally expanded by heat generated from the anode target. Even in the case where the axial gap is secured,
The preloader included in the preload structure with respect to the bearing positioned on the upper side along the gravity direction in a state where the orientation of the rotary anode is in a direction in which the rotation axis direction coincides with the gravity direction, The axial width of the axial gap in contact with the spacer becomes 0, and the position of the rotary anode is included in the preload structure for each of the bearings in a state in which the rotation axis direction is aligned with the horizontal direction. The axial gap is formed between the preloader and the bearing spacer.
Rotating anode type X-ray tube device. The rotary anode type X-ray tube device according to claim 1,
An X-ray control device for applying a high voltage to the rotating anode X-ray tube device;
An X-ray imaging apparatus comprising:

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