JP4360952B2 - Rotating anode type X-ray tube device - Google Patents

Description

  The present invention relates to a rotary anode X-ray tube apparatus and a method for manufacturing the same, and more particularly to a rotary anode X-ray tube apparatus suitable for an ultra-high speed scan CT scanner. In a rotating anode X-ray tube using a hydrodynamic slide bearing that uses a liquid metal lubricant, the rotating anode can be safely pivotally supported with a relatively small rotational torque even when the large-capacity rotating anode receives a very large centrifugal force. It is devised so that it can.

  In recent years, it has become increasingly important to shorten the scan time of X-ray CT scanners. At present, the shortest scan time is about 0.37 seconds, and further reduction of the scan time is strongly demanded. The X-ray CT scanner that is currently widely used has a rotating base that rotates mechanically, and a rotating anode X-ray tube device is attached at a position about 74.5 cm away from the center axis of rotation. The rotary anode type X-ray tube device is rotated once around the rotation center axis of the gantry within the scanning time. Therefore, if the acceleration of gravity is G, the scan time is about 23G when the scan time is 0.37 seconds, about 34G when the scan time is 0.30 seconds, and about 76G when the scan time is 0.20 seconds. When 0.15 seconds, the centrifugal acceleration of about 134G is received. Until now, it was one of the main obstacles to shortening the scanning time of an X-ray CT scanner that a rotating anode X-ray tube device that could withstand such a large centrifugal acceleration could not be realized.

  As is well known, a rotary anode type X-ray tube is a stator electromagnetic coil that is arranged outside a vacuum vessel by supporting a disk-shaped X-ray target rotatably in a vacuum vessel with a rotating body and a fixed body having bearings. The X-ray target is radiated to the surface of the X-ray target to emit X-rays while the X-ray target is rotated at a high speed in the vacuum vessel and accelerated and emitted from the cathode. The bearing portion is a rolling bearing such as a ball bearing, or a helical groove formed on the bearing surface and a liquid metal lubricant such as gallium (Ga) or gallium-indium-tin (Ga-In-Sn) alloy. It is constructed using a hydrodynamic slide bearing filled in the gap. Examples of the use of the latter plain bearing include, for example, JP-B-60-21463, JP-A-60-97536, JP-A-62-2287555, JP-A-2-227947, JP-A-2-227948, JP-A-2-227948. No. 2-244545, Japanese Patent Laid-Open No. 5-13028, US Pat. No. 4,210,371, US Pat. No. 4,562,587, USP 5068885, or US Pat. No. 5,077,776.

  When a rolling bearing such as a ball bearing is used for the bearing portion, an excessive pressure is applied to a small surface, so that it cannot withstand such a large load. Even when the conventional hydrodynamic slide bearing is used, there is a limit to the size of the bearing part and the torque required to rotate the rotating anode, that is, the rotational torque. Until now, the above rotating anode X-ray tube apparatus has not been realized. The operation of the bearing portion of the rotary anode X-ray tube using the hydrodynamic slide bearing will be described with reference to the drawings.

FIG. 13 (a) shows an example of a conventional dynamic pressure slide bearing for an X-ray tube, and FIG. 13 (b) shows the distribution of the pressure generated in the radial bearing portion at a light load at the axial position. Show. In FIG. 13A, reference numeral 1001 denotes a cylindrical bearing rotating body constituting a part of the rotating anode, and reference numeral 1002 denotes a columnar bearing fixed body inserted into the bearing rotating body 1001. A spiral bearing groove 1003 is provided on the surface of the bearing fixed body 1002, and a small bearing gap 1004 is provided at a fitting portion between the bearing fixed body 1002 and the bearing rotating body 1001. The liquid metal lubricant is filled to constitute first and second radial bearings 1005 and 1006 that receive a radial load. In order to give generality, the case where the bearing width Lb1 of the first radial bearing 1005 is larger than the bearing width Lb2 of the second radial bearing 1006 is shown. Reference numerals 1021 and 1022 denote a pair of thrust bearings configured similarly. The bearing rotating body 1001 is connected to an X-ray target (not shown) located on the right side of the figure. When the bearing rotating body 1001 rotates around the center axis 1008 at an appropriate speed and the external force 1007 perpendicular to the center axis 1008 applied to the bearing rotating body 1001 is sufficiently small, the bearing rotating body 1001 The central shaft 1008 substantially coincides with the central shaft 1009 of the bearing fixed body 1002, and a uniform pressure in the circumferential direction is distributed in the axial direction as shown in FIG. Reference numeral 1011 denotes a pressure distribution in the first radial bearing 1005, and reference numeral 1012 denotes a pressure distribution in the second radial bearing 1006. Lb1 and Lb2 represent the respective bearing widths, Lg represents the width of the low pressure region between the bearings, and Lt represents the total bearing length. The pressure in each bearing is highest at the center of each bearing.

  FIG. 14 shows an enlarged view of the bearing gap portion of FIG. 13 in order to explain the operation when the external force 1007 applied to the bearing rotating body 1001 increases. In FIG. 14, the thrust bearing is omitted. FIG. 14A shows the center of gravity GX of the entire rotating portion of the rotating anode including the bearing rotating body 1001 at the position where the center of gravity coordinates, that is, the distance from the right end of the radial bearing 1005 in the drawing, is L1, and is applied to the center of gravity GX. The state when the external force 1007 to be performed is sufficiently small is schematically shown. In this case, the center axis 1008 of the bearing rotating body 1001 substantially coincides with the center axis 1009 of the bearing fixed body 1002. When the external force 1007 applied in a direction perpendicular to the center axis 1008 of the bearing rotating body 1001 increases, the center axis 1008 of the bearing rotating body 1001 is not connected to the bearing fixed body 1002 as described in US Pat. No. 3,602,555. Inclined with respect to the central axis 1009.

  In the conventional rotary anode X-ray tube, the opposed surfaces of the bearing rotating body 1001 and the bearing fixed body 1002 are configured in parallel with each other, and the bearing gaps 1004 are uniformly distributed in the direction of the rotation center axis. Accordingly, when the external force 1007 is increased, the rotation center shaft 1008 is moved and inclined as schematically shown in FIG. 14B, and the surface of the end portion of the bearing rotating body 1001 is the surface of the bearing fixed body 1002. The surface of the other end portion of the bearing rotating body 1001 is inclined with respect to the surface of the end portion B on the opposite side of the bearing fixing body 1002 in the state of being inclined with respect to the surface. In close proximity to this. This situation is also described in JP-A-10-17283 and JP-A-2002-25483. The limit of the allowable external force 1007 is caused by the fact that the surface of the end A or the end B is close to the facing surface to the size of the surface roughness. Japanese Patent Laid-Open No. 2002-25483 describes that the surfaces facing each other at the end A and the end B are in contact with each other at the time of starting rotation or stopping, but the same applies when the external force 1007 increases. It is obvious that there is a problem.

  In the conventional rotary anode X-ray tube, the center-of-gravity coordinate L1 is a small value due to dimensional restrictions. When the center of gravity GX of the entire rotating portion of the rotating anode is positioned on the opposite side of the end B with respect to the end A as in the example shown in Japanese Patent Laid-Open No. 2003-51279, that is, the center of gravity coordinate L1 is negative. May be a value. In this case, the above effect becomes more remarkable. Even in these cases, when the external force 1007 is sufficiently small as in the conventional rotary anode X-ray tube, it can be used without any problem. However, it cannot be used for the purpose of realizing an ultra-high speed scan type CT scanner as described above because the radial load capacity is insufficient.

  In general, the radial load capacity, that is, the limit radial load that the radial bearing can support, increases the diameter of the bearing rotating body 1001 and the bearing fixed body 1002, increases the total length Lt of the bearing, and the bearing gap 1004. It can be increased by narrowing. However, these methods are not suitable for the following reasons as a rotary anode type X-ray tube used for an ultrafast scanning CT scanner. When the diameter of the bearing is increased or the total length of the bearing is increased, the entire X-ray tube apparatus is increased, and the mount on which the X-ray tube apparatus is mounted becomes excessive. In addition, these methods all increase the rotational torque. In particular, the influence of the bearing clearance dimension is important as described below. The radial load capacity and rotational torque of the first radial bearing 1005 in the conventional structure shown in FIGS. 13 and 14 having a uniform bearing gap 1004 in the central axis direction and various dimensions of the bearing gap 1004. FIG. 15 shows the relationship. FIG. 15 shows values calculated for a case where the diameter of the bearing rotating body 1001 is 60 mm, the bearing width Lb1 is 70 mm, the total length Lt is 112 mm, and the rotational speed is 6000 rpm.

  According to FIG. 15, it can be seen that the radial load capacity increases by reducing the size of the bearing gap 1004, but the rotational torque required in this case also increases. Since the rotational torque of the X-ray tube is generated by an induction motor having a large gap between the rotor and the stator, the magnitude of the rotational torque is limited. Further, when the rotational torque is large, there is a problem that loss at the bearing portion is large and heat generation at the bearing portion becomes excessive. FIG. 16 shows the relationship between the dimension of the bearing gap 1004 that is uniform in the central axis direction and the rotational torque at no load. As can be seen from FIG. 16, when the size of the bearing gap 1004 is reduced, the rate of change in rotational torque with respect to the size of the bearing gap increases. For example, when the bearing gap dimension is 10 μm, the rotational torque increases by about 11% when the bearing gap dimension is reduced by 1 μm.

In the bearing used for the rotary anode type X-ray tube, the bearing is made compact due to dimensional limitations. When a large external force as described above is applied, the bearing rotating body 1001 or the bearing fixed body 1002 is minute. It is inevitable that mechanical mechanical deformation occurs. Further, heat from the X-ray target flows into the rotary anode X-ray tube bearing, and temperature rises due to heat generation due to bearing loss, etc., which causes thermal expansion and changes in the bearing gap size. In addition, since a liquid metal lubricant such as a Ga alloy is used as the lubricant, the bearing clearance dimension may further vary due to a reaction with the surface member of the bearing. Japanese Patent Application Laid-Open No. Hei 8-102277 and US Pat. No. 5,483,570 describe that fragments are generated due to a number of causes such as liquid metal oxidation, mechanical wear, and chemical corrosion. For these reasons, it is difficult to keep the bearing gap dimension at 10 μm or less over the entire bearing length Lt, and it is preferable to keep it at about 15 μm or more. In this case, as shown in FIG. 15, a sufficiently large radial load capacity as described above cannot be obtained. As described above, the conventional X-ray tube could not realize a compact rotating anode X-ray tube apparatus that can be used for the above-described ultrahigh-speed scanning CT scanner.
Japanese Patent Publication No. 60-21463 JP-A-60-97536 JP-A-62-287555 JP-A-2-227947 JP-A-2-227948 JP-A-2-244545 Japanese Examined Patent Publication No. 3-77617 Japanese Patent Laid-Open No. 5-13028 JP-A-8-102277 JP-A-10-17283 JP 11-96949 A Japanese Patent Laid-Open No. 11-149892 Japanese Patent Laid-Open No. 11-224627 JP 2002-25483 A JP 2003-51279 A USP 3602555 gazette US Pat. No. 4,210,371 US Pat. No. 4,562,587 US Pat. No. 4,644,577 USP 4856039 USP 5068885 USP 5077776 US Pat. No. 5,483,570

  The problem to be solved is to provide a compact rotating anode X-ray tube device that can be used in an ultra-high speed scanning CT scanner and can withstand extremely high centrifugal acceleration. In particular, in a bearing used for a rotary anode X-ray tube, the radial load capacity is sufficiently large, the rotational torque is sufficiently small, and the mechanical deformation of the bearing is allowed to be improved.

  In the present invention, a radial bearing comprising a hydrodynamic slide bearing using a liquid metal as a lubricant is provided in the rotating mechanism of the rotary anode X-ray tube, and the radial bearing is provided so as to increase the load capacity with a small rotational torque. It has improved. The rotary anode X-ray tube preferably includes at least two radial bearings that are substantially subjected to a radial load. From the dimensions of the bearing gaps in the adjacent regions of the two radial bearings. However, the size of the bearing gap in the other end region of each of the radial bearings is large. Since the average dimension of the bearing gap in the direction along the rotation center axis is large, the rotational torque is sufficiently small when the radial load is small. When the radial load increases, the central axis of the bearing rotating body is inclined at a minute angle, and the opposing bearing surfaces approach each other while decreasing the inclination angle between the opposing bearing surfaces. The closer the area is, the larger the area of the region where a large pressure is generated, which acts to have a very large radial load capacity. That is, when the rotation center axis is tilted, the rate of increase of the total rebound pressure with respect to the tilt angle increases rapidly. In this case, the rotational torque increases, but is a smaller value than that of the conventional structure, and can be within the allowable range. Further, when the radial load increases, the inclination angle of the central axis of the bearing rotating body is extremely small and does not substantially affect the operating characteristics of the rotating anode X-ray tube.

  As described above, the dimension of the bearing gap is a function of the position in the direction along the rotation center axis, and even when the bearing rotating body or the bearing fixed body is mechanically deformed by a large external force, these surfaces are unique. The function is determined in advance so as not to cause inconvenience such as abnormal close proximity of the minute portion. When a predetermined large radial load is applied and the central axis of the bearing rotating body is tilted, the adjacent bearing surface portions that approach each other approach more uniformly while maintaining a uniform gap in the direction along the central axis of rotation. Thus, a great pressure is devised so that it is generated in a wide area.

  The depth dimension of the bearing groove is preferably between the maximum value and the minimum value of the bearing clearance dimension, and even if the dimension is uniform in the direction along the rotation center axis, it varies with the position. It may be a value. In this case, it operates stably both when the radial load is small and when the radial load is large. Since the device has been devised as described above, the operation is stable even when a large radial load is applied, and the above-described problem has been solved. More specific problem-solving means employed in the present invention are as follows.

One of the present invention comprises a vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having the fixed body and coaxially fitted portion, the rotation body A rotary anode X-ray tube comprising an attached X-ray target and a radial bearing that substantially supports the rotating body, wherein at least one of the radial bearings includes a first surface of the stationary body. A second surface of the rotating body facing the first surface with a small bearing gap, a spiral groove provided on at least one of the first surface and the second surface, And a fluid pressure type sliding bearing containing a liquid metal lubricant filled in the first surface and / or the second surface, wherein the rotating body forms an inclination angle with respect to the fixed body. The same when tilted to the maximum within the allowable range. The circumferential proximity portion that is closest to the opposing surface in the circumferential direction at the directional position is formed to include a contact portion that substantially eliminates the gap between the opposing surfaces, and the contact portion is continuously or The rotary anode X-ray tube is characterized by intermittently spreading in the axial direction over a predetermined width. In this rotary anode X-ray tube, the larger the external force acts on the rotary anode and the more the central axis of the rotary anode is inclined with respect to the central axis of the fixed body, the closer the surface of the rotary body is to the near side. The area where the repulsive pressure is generated is larger because the portion that approaches while the angle formed with the surface of the fixed body on the side to be smaller becomes smaller in the bearing width direction. Increasing with angle produces a large total rebound pressure. As a result, a large radial load capacity is obtained, and a rotating anode type X-ray tube that can be used for an ultrafast scanning CT scanner can be realized. Here, the circumferentially adjacent portion is a surface in which a bearing groove is provided, a surface that forms the hill, and a surface in which no bearing groove is provided, the surface is a specific axial direction. Represents the surface portion closest to the facing surface in the circumferential direction of the bearing, and the contact portion is a surface provided with a bearing groove, and the surface forming the hill is provided with the bearing groove. In the case of an unfinished surface, the surface represents a portion in which the gap between the opposite surfaces is substantially eliminated. Further, the inclination angle represents an angle formed by a substantial central axis of the rotating body and a substantial central axis of the fixed body, and the allowable range is that the rotating body is not rotated. In the state, the inclination angle when the external force equivalent to the actual operation condition of the rotary anode X-ray tube is applied to the center of gravity of the entire rotating portion of the rotary anode is shown. In the present invention, it is preferable that the predetermined width is equal to the entire bearing width, but even a narrower width is effective, and thus is determined according to a required radial load capacity.

One of the present invention comprises a vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having the fixed body and coaxially fitted portion, the rotation body A rotary anode X-ray tube comprising an attached X-ray target and a radial bearing that substantially supports the rotating body, wherein at least one of the radial bearings includes a first surface of the stationary body. A second surface of the rotating body facing the first surface with a small bearing gap, a spiral groove provided on at least one of the first surface and the second surface, And a fluid pressure type sliding bearing containing a liquid metal lubricant filled in the first surface and / or the second surface, wherein the rotating body forms an inclination angle with respect to the fixed body. If the maximum tilt is within the allowable range, A cross section including the tilt angle of the body and the rotating body at the same axial position of the first intersecting line and the second intersecting line formed by intersecting the first surface and the second surface, respectively. Includes a small inclination difference portion formed so that an angle between tangents formed by the tangent lines is smaller than the inclination angle. The small inclination difference portion is predetermined in the axial direction continuously or intermittently. It is a rotating anode type X-ray tube characterized in that it extends over the width. In this rotary anode X-ray tube, the larger the external force acts on the rotary anode and the more the central axis of the rotary anode is inclined with respect to the central axis of the fixed body, the closer the surface of the rotary body is to the near side. Since the angle formed with the surface of the fixed body on the side to be fixed approaches closer, the area where a larger repulsive pressure is generated increases and a large total repulsive pressure is generated. As a result, a large radial load capacity is obtained, and a rotating anode type X-ray tube that can be used for an ultrafast scanning CT scanner can be realized. The inclination angle represents an angle formed by a substantial central axis of the rotating body and a substantial central axis of the fixed body, and the allowable range is a state in which the rotating body is not rotating. The inclination angle when an external force equivalent to the actual operating condition of the rotating anode type X-ray tube is applied to the center of gravity of the entire rotating portion of the rotating anode is shown. The cross section including the inclination angle represents a plane including the central axis of the fixed body and the central axis of the rotating body inclined with respect to the fixed body. In the present invention, it is preferable that the predetermined width is equal to the entire bearing width, but even a narrower width is effective, and thus is determined according to a required radial load capacity.

One of the present invention comprises a vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having the fixed body and coaxially fitted portion, the rotation body A rotary anode X-ray tube comprising an attached X-ray target and a radial bearing that substantially supports the rotating body, wherein at least one of the radial bearings includes a first surface of the stationary body. A second surface of the rotating body facing the first surface with a small bearing gap, a spiral groove provided on at least one of the first surface and the second surface, And a fluid pressure type sliding bearing containing a liquid metal lubricant filled in the first surface and / or the second surface, wherein the rotating body forms an inclination angle with respect to the fixed body. If the maximum tilt is within the allowable range, Including an adjacent surface portion formed so as to approach the opposing surface at an axial position other than the endmost position of the plain bearing, at least as much as the extent at the endmost position. The rotary anode X-ray tube is characterized in that it spreads over a predetermined width in the axial direction either periodically or intermittently. In this rotary anode type X-ray tube, when a large external force acts on the rotary anode and the central axis of the rotary anode is inclined with respect to the central axis of the fixed body, the surface of the rotary body other than the endmost part of the bearing And the surface of the fixed body approach at the same level or more in a predetermined width, the area where the repulsive pressure is larger than that in the conventional case increases and a large total repulsive pressure is generated. In addition, since the endmost portion does not approach too much at the beginning, inconvenience such as galling hardly occurs. As a result, a radial load capacity larger than the conventional one can be obtained. The inclination angle represents an angle formed by a substantial central axis of the rotating body and a substantial central axis of the fixed body, and the allowable range is a state in which the rotating body is not rotating. The inclination angle when an external force equivalent to the actual operating condition of the rotating anode type X-ray tube is applied to the center of gravity of the entire rotating portion of the rotating anode is shown. In the present invention, it is preferable that the predetermined width is equal to the entire bearing width, but even a narrower width is effective, and thus is determined according to a required radial load capacity.

  One aspect of the present invention is that in any one of the above-described inventions, the first surface and / or the second surface is formed on the fixed body when the rotating body is positioned coaxially with the fixed body. A first crossing line and a second cross section of the rotating body, including the central axis of the rotating body, intersecting the first surface and the second surface, respectively, on the same side with respect to the central axis. When the number of the hydrodynamic slide bearings is one, in the case where there is a single hydrodynamic slide bearing, in the vicinity of the extreme end of both, the crossing line of 2 A rotary anode type X-ray characterized in that it includes a surface portion formed so as to relatively spread along the central axis toward each of the extreme ends in the vicinity of both extreme ends. It is a tube. In this rotary anode type X-ray tube, when the rotary body is inclined with respect to the fixed body, the surface of the rotary body is larger than the surface of the fixed body at the end of one of the radial bearings. A portion having an area approaches to generate a large repulsive force, and the surface of the rotating body and the surface of the fixed body approach each other at a portion having a larger area than the conventional one at the other end portion of the radial bearing. A large repulsive force is generated in a direction substantially opposite to the above. As a result, a radial load capacity larger than the conventional one can be obtained. The angle formed by the first intersecting line and the second intersecting line is approximately the same as the angle at which the rotating body can be tilted with respect to the fixed body. Since the opposing surfaces on the side are parallel to each other, it is preferable.

  One aspect of the present invention is that in any one of the above inventions, any one of the dynamic pressure type slide bearings has the bearing gap having a first bearing gap dimension at the extreme end position, and other than the extreme end position. A second bearing gap dimension that is smaller than the first bearing gap at the position, and a bearing gap between the first bearing gap dimension and the second bearing gap dimension at an intermediate position between them. A rotary anode type X-ray tube characterized in that its dimensions change with the axial position. In this rotary anode type X-ray tube, when the rotating body is inclined with respect to the fixed body, the rate of change in the bearing width direction of the distance between the bearing surfaces on the adjacent side becomes smaller than the conventional one. Since the surface of the rotating body and the surface of the fixed body are close to each other at a portion having a larger area with a relatively small inclination and increased parallelism, a large repulsive force is generated. As a result, a radial load capacity larger than the conventional one can be obtained. The rate of change in the bearing width direction of the bearing gap dimension is preferably a value in which the bearing surfaces come into contact with each other in the widest possible range when the rotating body is inclined to the maximum with respect to the fixed body. . The second bearing gap dimension is preferably 15 μm or less, more preferably about 5 μm. The first bearing gap dimension is preferably 15 μm or more, more preferably about 40 μm or more.

  One aspect of the present invention is that in any one of the dynamic pressure type plain bearings according to the present invention, the bearing gap is maintained substantially in the size of the second bearing gap and continues over a predetermined width in the bearing width direction. A rotary anode type X-ray tube characterized by including a portion configured as described above. In this rotary anode type X-ray tube, since the bearing gap dimension is limited not to be smaller than the second bearing gap dimension over the entire bearing width of the hydrodynamic slide bearing, the surface of the rotating body and the It is possible to prevent the surface of the fixed body from being partly abnormally approached and to obtain a larger radial load capacity than the conventional one as described above.

  One of the present invention, in any one of the above inventions, includes first and second radial bearings comprising the hydrodynamic slide bearing, wherein the rotating body is positioned coaxially with respect to the fixed body. In the regions of the first and second radial bearings located on the side farther from each other than the dimensions of the bearing gaps in the regions located closer to each other in the axial direction of the first and second radial bearings. The first surface and / or the second surface is formed at least partially such that the dimensions of the bearing gap increase sequentially with the axial position toward the respective ends. It is a featured rotating anode type X-ray tube. In this rotary anode type X-ray tube, when the rotary body is inclined at an inclination angle with respect to the fixed body, the opposing bearing surfaces of both the radial bearings are approached with increased parallelism. Both radial bearings produce a greater total pressure than before. As a result, a radial load capacity larger than the conventional one can be obtained. The axial distribution of the size of the bearing gap is preferably determined so that both bearing surfaces contact each other in the widest possible range when the rotating body is tilted to the maximum with respect to the fixed body. .

  One of the present invention, in any one of the above-mentioned inventions, includes first and second radial bearings composed of the hydrodynamic slide bearing, and the first surface and / or the first radial bearing and / or The second surface includes at least one of the contact portion, the small inclination difference portion, or the proximity surface portion on one side with respect to the central axis of the fixed body, and the second radial bearing. The constituting first surface and / or the second surface includes at least one of the contact portion, the small inclination difference portion, or the proximity surface portion on the opposite side to the central axis of the fixed body. It is a rotary anode type X-ray tube characterized by the above. In this rotary anode type X-ray tube, when the rotating body is inclined at an inclination angle with respect to the fixed body, the surface portions that are closest to each other are not localized at both end positions of the bearing. Furthermore, the bearing surfaces facing each other at both ends are spread in the axial direction, and the extent of the spread is such that the bearing surfaces facing as wide a range as possible when the inclination angle is within the allowable value. It is preferably determined to contact. It is preferable that the contact portion, the small inclination difference portion, or the proximity surface portion extends in the axial direction over a predetermined width in each of the first radial bearing and the second radial bearing.

One aspect of the present invention includes the first and second radial bearings each including the hydrodynamic slide bearing in any one of the above-described inventions. In the case where the first and second radial bearings are positioned in the same axis, the first and second radial bearings are located in regions adjacent to each other in the axial direction. to those who are engaged, the diameter of the outer surface, the other end portion of said first radial bearing, of the person who is fitted inside with one of the fixed body or the rotating body, than the diameter of the outer surface is large, located in the adjacent regions, the at one end portion of the second radial bearing, of the person who has been fitted to the inside in one of the fixed body or the rotating body, the outer surface diameter, said second At the other end of the radial bearing That the fixed body or who the is fitted inwardly of the rotating body, larger than the diameter of the outer surface, and, among those who said being fitted to the outside among the rotating body or the fixed body The rotary anode type X-ray tube is characterized in that the surface has a portion that is not parallel to the outer surface facing the surface. In this rotating anode X-ray tube, by varying the outer diameter of the person who is fitted inside with one of the fixed body or the rotating body in the axial direction, the rotation mechanism is easily related to the one of the invention A large radial load capacity can be obtained as compared with the prior art while being manufactured and inexpensive. In this case, the diameter of the inner surface of the fitting portion on the outer side is constant over the entire bearing width, so making it easier to manufacture, preferred.

One aspect of the present invention includes the first and second radial bearings each including the hydrodynamic slide bearing in any one of the above-described inventions. Out of the rotating body or the fixed body at one end of the first radial bearing, where the first and second radial bearings are located in regions adjacent to each other in the axial direction when positioned coaxially of people who have engaged in, the diameter of the inner surface at the other end portion of said first radial bearing, of who the is fitted to the outside among the rotating body or the fixed body, than the diameter of the inner surface is small, located in the adjacent regions, the at one end portion of the second radial bearing, of who the is fitted to the outside among the rotating body or the fixed body, the diameter of the inner surface, the second At the other end of the radial bearing That, towards said fitted and outwardly of the rotating body or the fixed body, smaller than the diameter of the inner surface and the outer of the person who has been fitted to the inside in one of the fixed body or the rotating body The rotary anode type X-ray tube is characterized in that the surface has a portion that is not parallel to the inner surface facing the surface. In this rotating anode X-ray tube, wherein the inner diameter of the person who is engaged outwardly of the fixed body or the rotating body varying in the axial direction, the production either of the rotating mechanism according to the invention is readily It is possible to obtain a larger radial load capacity than the conventional one while being inexpensive. In this case, the diameter of the outer surface of the fitting portion inside a constant over the entire bearing width, so making it easier to manufacture, preferred.

  One aspect of the present invention includes the first and second radial bearings each including the hydrodynamic slide bearing in any one of the above-described inventions. When positioned coaxially, a central section perpendicular to the central axis of the fixed body at the center in the axial direction of the region sandwiched between the first radial bearing and the second radial bearing is the second radial bearing. From the circle formed by crossing the surface or its extended surface, the circular cross section formed by crossing the first surface at the far end of each radial bearing and intersecting with the first surface is substantially conical. The first surface is formed at least partially so as to be in line with each other, or from the circle in which the central cross-section intersects the first surface or an extension thereof. At least a portion of the second surface is such that an end section perpendicular to the central axis at the far end of the bearing substantially conforms to a conical surface that can be expected to intersect with the second surface. The rotary anode X-ray tube is characterized in that it is formed. In this rotary anode type X-ray tube, when the rotary body is inclined at an inclination angle with respect to the fixed body, the surface of the rotary body and the surface of the fixed body constituting the first radial bearing The rotational difference between the intersections formed by crossing the cross section including the inclination angle on the adjacent surface side is smaller than that in the prior art, and constitutes the second radial bearing. Both radial bearings have a smaller difference in radial distance on the adjacent surface side between intersecting lines formed by crossing the cross section including the inclination angle between the surface of the body and the surface of the fixed body, compared to the conventional case. Produces a greater total pressure than before. As a result, a radial load capacity larger than the conventional one can be obtained. The angle formed between the bearing surface along the conical surface and the bearing surface opposite to the bearing surface is substantially equal to the maximum inclination angle when the rotating body is inclined at a maximum inclination angle with respect to the fixed body. It is preferable. In the present invention, the central cross section represents a plane orthogonal to the central axis of the fixed body at the axial center position, and the end cross section is aligned with the central axis of the fixed body at the axial end position. An orthogonal plane is shown, and the extension surface is a surface obtained by extrapolating or interpolating each surface and extending in the axial direction.

One of the present invention comprises a vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having the fixed body and coaxially fitted portion, the rotation body In the rotary anode X-ray tube comprising an X-ray target attached and first and second radial bearings that substantially support the rotary body, each of the first and second radial bearings is A first surface of the fixed body; a second surface of the rotating body facing the first surface with a minute bearing gap; at least one of the first surface and the second surface; A hydrodynamic slide bearing including a spiral groove provided in the liquid metal lubricant and a liquid metal lubricant filled in the spiral groove, and the rotating body substantially coincides with the central axis of the fixed body. Bearing clearance of each radial bearing when rotating The respective bearings are configured so that the pressure generated at the center is distributed at the maximum in the central portion of each bearing, and the center of gravity of the entire rotating portion including the rotating body is the axial center of the first radial bearing. A rotary anode type X-ray tube configured to be located in an axial region sandwiched between a position and an axial center position of the second radial bearing. In this rotary anode type X-ray tube, when a large external force is applied to the rotating body, the inclination angle of the rotating central axis with respect to the central axis of the fixed body becomes small. The difference due to the directional position becomes small, and the radial load capacity tends to increase.

One of the present invention comprises a vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having the fixed body and coaxially fitted portion, the rotation body In the rotary anode X-ray tube comprising an X-ray target attached and first and second radial bearings that substantially support the rotary body, each of the first and second radial bearings is A first surface of the fixed body; a second surface of the rotating body facing the first surface with a minute bearing gap; at least one of the first surface and the second surface; A hydrodynamic slide bearing including a helical groove provided in the liquid crystal and a liquid metal lubricant filled therein, the diameter and the bearing width of the first radial bearing, and the second radial bearing. The diameter and the bearing width are substantially the same, A rotary anode type characterized in that the center of gravity of the entire rotating part including the rotary member is located at a substantially central position in the axial direction between the first radial bearing and the second radial bearing. X-ray tube. In this rotary anode type X-ray tube, when a large centrifugal force acts on the rotating body, no rotational moment is generated by the first and second radial bearings, and the rotating body is not inclined and is not inclined. Due to the displacement, a large pressure is generated over a large area between the first surface and the second surface approaching each other, and a large radial load capacity can be obtained. In this rotary anode type X-ray tube, it is preferable that the surface of the rotating body and the surface of the fixed body are respectively constant in the bearing width direction, because manufacturing is easy. Further, the size of the bearing gap is preferably larger than 15 μm because the rotational torque at light load can be reduced and the production is easy. The position of the center of gravity is preferably exactly the same as the center position, but it is allowed even if the center of gravity is separated from the center position by a distance that can be limited to such an extent that the inclination of the rotating body can be substantially ignored.

  One aspect of the present invention is the method according to any one of the above-described aspects, in which the radial dimension of each radial bearing including the hydrodynamic slide bearing is determined in the axial direction over the entire width of each bearing width. A rotating anode type X-ray tube characterized in that the average value is larger than 15 μm. With this rotating anode type X-ray tube, the rotational torque at light load can be reduced, the production is easy, the deformation of the rotating body or the fixed body can be allowed, and the change in the bearing clearance dimension with time. It has features such as being acceptable, and a large radial load capacity can be obtained.

  One of the present invention is the invention according to any one of the above-mentioned inventions, wherein the depth dimension of the bearing groove constituting each of the radial bearings composed of the hydrodynamic slide bearing is equal to or greater than the minimum value of the bearing clearance dimension. It is a rotary anode type X-ray tube characterized by having a dimension less than the maximum value. In this rotary anode type X-ray tube, a large radial load capacity can be obtained while being easy to manufacture. Moreover, it is easy to maintain a stable operation even if the operating conditions change. It is preferable that the depth of the bearing groove be substantially the same dimension over the entire bearing width because it is easy to manufacture.

One of the present invention comprises a vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having the fixed body and coaxially fitted portion, the rotation body A rotary anode X-ray tube comprising: an attached X-ray target; and at least one radial bearing comprising a hydrodynamic slide bearing using a liquid metal as a lubricant and substantially supporting the rotating body. in the manufacturing method, the fixed body so as to have a first surface, said rotary body to have a second surface, forming an inclination angle the rotary body fitted in as normal to the fixed body Then, when the tilt is maximized within an allowable range, a first intersection line formed by a cross section including the tilt angle of the fixed body and the rotating body intersecting the first surface and the second surface, respectively. And the second intersection line at the same axial position. A small inclination difference portion in which an angle between tangent lines formed by the respective tangent lines becomes smaller than the inclination angle, and the small inclination difference portion spreads continuously or intermittently over a predetermined width in the axial direction. As described above, the step of processing the fixed body and / or the rotary body, the step of forming a spiral groove on the first surface of the fixed body or the second surface of the rotary body, the fixed body and the rotation a step of supplying the liquid metal lubricant in the gap formed by being sandwiched between the when fitting a body, a method of manufacturing a rotating anode X-ray tube, which comprises a. In particular, the fixed body and said rotating body, or in place of the one in the jigs and tools suitable shape, fitted in a state filled with abrasive into the gap, equivalent to that applied at the time of actual operation It is preferable to include a step of performing surface processing while applying pressure to each other while applying the external force to a place located at the center of gravity of the entire rotating portion of the rotating anode. When this manufacturing method is adopted, the relative relationship between the opposing surfaces becomes good during operation, and a rotating anode X-ray tube that can withstand extremely large centrifugal force can be easily produced. The inclination angle represents an angle formed by a substantial central axis of the rotating body and a substantial central axis of the fixed body, and the allowable range is not supplied with the liquid metal lubricant. In the state where the rotating body is not rotating, a predetermined external force equal to or less than the actual operating condition of the rotating anode type X-ray tube is applied to a place corresponding to the center of gravity position of the entire rotating portion of the rotating anode. It represents the tilt angle when it is done. The cross section including the inclination angle represents a plane including the central axis of the fixed body and the central axis of the rotating body inclined with respect to the fixed body. The regular street represents a state having a relative relation equivalent to actual use.

  One aspect of the present invention is a rotary anode X-ray tube according to any one of the above inventions, or a rotary anode X-ray tube manufactured by the method according to the above invention, and a storage for storing the rotary anode X-ray tube. Rotating torque is applied to the rotating body in the rotating anode X-ray tube from outside the vacuum container of the rotating anode X-ray tube, a holding mechanism for fixing the rotating anode X-ray tube to the storage container, and A rotating anode type X-ray tube device comprising: a stator to be provided; and means for supplying a negative high voltage to a cathode that emits electrons in the rotating anode type X-ray tube. The high voltage supply means includes, for example, an in-pipe wiring, a high voltage connector, a high voltage cable, or the like. Since this rotating anode type X-ray tube device can withstand extremely large centrifugal force as compared with the prior art, the use of this X-ray tube device device makes it possible to realize an ultra-high speed scanning CT scanner that was not previously realized. .

  One aspect of the present invention is a rotary anode X-ray tube according to any one of the above inventions, a rotary anode X-ray tube manufactured by the method according to the above invention, or a rotary anode X-ray tube apparatus according to the above invention. And a rotating gantry that can be rotated about the central axis by mounting it, a stationary gantry that rotatably supports the rotating gantry, and the rotating anode X-ray tube or the rotating anode X-ray tube device. An X-ray CT comprising: an X-ray detector that detects X-rays transmitted through the irradiated object; and a device that displays a cross section of the irradiated object using an output of the X-ray detector. It is a scanner. With this X-ray CT scanner, it is possible to obtain a tomographic image with better time resolution by shortening the scanning time than before.

  By adopting the present invention, a compact rotary anode X-ray tube device that has a very large anode heat capacity and can withstand extremely large centrifugal force can be easily and stably produced without requiring any special process or special manufacturing equipment. It is possible to provide a rotary anode type X-ray tube apparatus that can be mass-produced and can be used for an ultrahigh-speed scanning CT scanner that has not existed before. Specifically, when a large centrifugal force acts on the rotating anode, the central axis of the rotating anode causes a slight displacement and tilts at a minute angle, but at this time the bearing surface does not hit one side. Not only does partial wear occur, but as the angle of inclination increases, the bearing surfaces are brought closer together in a substantially parallel manner, creating a large pressure over a large area. As a result, it is possible to obtain a radial load capacity that is about seven times larger than that of a rotary anode X-ray tube device that employs a conventional bearing of the same size and has the same rotational torque when no load is applied. Further, since the average value of the bearing clearance dimension in the direction along the rotation center axis is a large value, the rotational torque is a sufficiently small value. Not only is the rotational torque at no load small, but also the rotational torque is sufficiently small because the average value in the circumferential direction of the distance between the surfaces of the bearing gaps at both ends of the bearing is large even at high loads. Furthermore, even when the bearing rotating body or the bearing fixed body constituting the bearing is deformed to some extent by receiving a large radial load, it can be operated sufficiently stably. On the other hand, when used in applications where a large external force does not act, the rotary anode can be made smaller than before, so that a more compact rotary anode X-ray tube device can be provided.

  The best mode rotary anode X-ray tube according to the present invention includes first and second radial bearings and two thrust bearings composed of a hydrodynamic slide bearing using a liquid metal as a lubricant. Each of the plain bearings includes a rotation mechanism for generating a bearing force in a direction perpendicular to the rotation center axis of the rotary anode and a direction along the rotation center axis so as to rotatably support the rotary anode. The first and second radial bearings are coaxially formed with a separation distance from each other in the direction of the rotation center axis, and these radial bearings receive substantially the entire radial load of the rotary anode. . The first and second radial bearings have first and second ends, respectively, and the second end of the first radial bearing is between the first end of the second radial bearing. The bearing intermediate region is formed while maintaining a predetermined separation distance. The first end portion of the first radial bearing and the second end portion of the second radial bearing form a bearing front end region and a bearing rear end region, respectively. In the portion where the separation distance is maintained, the gap between the bearing rotating body and the bearing fixed body is sufficiently large so that substantially no pressure is generated in the lubricant made of liquid metal.

  In the first radial bearing and the second radial bearing, the size of the bearing gap in the vicinity of the bearing middle region is as small as about 5 μm, for example. The size of the bearing gap gradually increases toward the bearing front end region and the bearing rear end region, and is about 40 μm at the outermost end of the bearing front end region. The change in the axial direction of the bearing clearance dimension is such that a part of the surface of the bearing rotating body in the front end region of the bearing contacts the surface of the bearing fixed body facing, and the bearing rear end region of the bearing rotating body. When the rotation center axis is tilted to the maximum allowable level so that the surface of a part of the bearing is in contact with the surface of the bearing fixing body facing in the opposite direction, the surface of the bearing rotating body and the bearing fixing body On the side closest to the surfaces, these surfaces are determined to be substantially parallel to each other. That is, when the bearing rotating body is tilted in an arbitrary direction to the maximum extent, only the surface in the local region does not come into contact, and the entire bearing width approaches the same.

  The surfaces of the bearing rotating body and the bearing fixed body are extremely flat so as not to have sharp irregularities of, for example, 1 μm or more, and when they are close to each other, a part of the irregularities is not locally contacted and has a large area. It has a surface contact. In this way, when the bearing rotating body is tilted to the maximum extent, surface contact is made with a large area maintained. Accordingly, when the center of gravity of the entire rotating portion of the rotating anode is displaced due to a large external force and the center axis of the bearing rotating body is inclined with respect to the center axis of the bearing fixing body, the bearing rotating body When a part of the surface approaches the surface of the bearing fixed body facing the surface while maintaining a substantially parallel gap, the bearing rotating body tends to be further displaced or inclined due to an extremely large repulsive pressure from a lubricant over a wide surface. , The other end portion comes close to each other, and in the same manner as described above, a very large repulsive pressure is applied over a wide surface to reach equilibrium. In this case, the maximum value of the inclination angle of the central axis of the bearing rotating body is a sufficiently small value, and does not substantially have any adverse effect on the characteristics of the rotary anode type X-ray tube.

  In the conventional bearing having a bearing gap of a uniform dimension in the direction along the central axis of the bearing rotating body, the above-described action is achieved by keeping the central axis of the bearing rotating body and the central axis of the bearing fixing body parallel. This is similar to the case where the surface of the bearing rotating body approaches the surface of the bearing fixing body in a state of being in a state of being in a closed state. However, the central axes are displaced while being kept parallel to each other in this way because the first radial bearing and the second bearing have the same characteristics, and the center of gravity of the entire rotating portion of the rotating anode is Only in special cases where the radial position of both radial bearings is exactly the same. In an actual rotating anode X-ray tube, it is not easy and general to satisfy such a condition. When the bearing gap inclined in the axial direction as described above is provided, the center of gravity of the entire rotating portion of the rotating anode deviates from the end of the bearing or the bearing, as is the case with an actual rotating anode X-ray tube. Even if it is in the position, it will have a sufficiently large radial load capacity, and a rotary anode X-ray tube having a compact and large radial load capacity can be easily realized.

  When it is known that the bearing rotating body or the bearing fixed body undergoes elastic deformation when subjected to a predetermined radial load, the bearing rotation as described above is performed when the predetermined radial load is received. The axial distribution of the size of the bearing gap is a function of the axial position in consideration of the elastic deformation so that the surface of the body and the surface of the bearing fixed body approach each other while maintaining substantially the same distance. It is decided. Therefore, it is not necessary to increase the rigidity of the bearing rotating body or the bearing fixed body more than necessary, and a compact rotating anode can be realized.

When constituting the bearing part as described above, can be realized radial bearing with a very large radial load capacity while maintaining small rotational torque, provides a rotating anode X-ray tube which can be used for ultra high-speed scan type CT scanner can do. Hereinafter, the embodiment and operation of the present invention will be described more specifically and in detail using examples.

The structure and configuration of the rotary anode X-ray tube of the present invention will be described with reference to FIGS. In these drawings, the same parts are denoted by the same reference numerals. FIG. 1 is a cross-sectional view showing the main part of a rotary anode X-ray tube according to the present invention, wherein 1 is a vacuum vessel for keeping the internal vacuum space 1a at a high vacuum, and 2 is in the vacuum vessel 1. The cathode 3 emits electrons, 3 is an X-ray target that emits X-rays when electrons emitted from the cathode 2 are incident, and 4 is an X-ray target that emits X-rays from the X-ray target 3. It is the X-ray irradiation window for taking out outside. In FIG. 1, 10 is a rotation mechanism for rotatably supporting the X-ray target 3, 20 is a rotation structure for rotating the X-ray target 3 in the rotation mechanism 10 , and 30 is a rotation structure 20. a portion is a fixed structure for rotatably supporting the rotary structure 20 is fitted, 40 is a stator for imparting a rotational force to the rotary structure 20 from the outside of the vacuum container 1.

The rotary structure 20 includes a target support 21 to which the X-ray target 3 is coaxially attached, a first rotary body member 22 that is coaxially joined to the target support 21, and a first rotary body member 22. A second rotating body member 23 that is coaxially attached and a third rotating body member 24 that is coaxially attached to the second rotating body member 23 are included. The X-ray target 3 is attached to the tip of a target support 21 made of molybdenum alloy by an anode fixing screw 5, and the other end of the target support 21 is welded to one end 22 a of the first rotary member 22. The other end 22b of the first rotating member 22 is connected to one end 23a of the second rotating member 23 with a screw or the like, and the other end of the second rotating member 23 The portion 23b is connected to a part 24a of the third rotating member 24 by screws or the like (not shown). Further, a shielding cylinder 6 for shielding radiation heat from the X-ray target 3 is coaxially attached to the target support 21.

A rotor 26 is provided on the outer side of the first rotating body member 22 coaxially with the first rotating body member 22, and is joined by welding or the like in the vicinity of one end 22a of the first rotating body member 22. . The upper end portion of the third rotating body member 24 shown in the figure forms a rotating body diameter small portion 24b. A rotating lid 27 is connected to the upper end portion of the drawing by a screw or the like, and the lower end portion of the third rotating body member 24 is divided into two parts. The rotating annular bodies 28 are connected by screws or the like. The rotor 26 is made of a material having a high electrical conductivity such as copper, and the lower half of the rotor 26 in the drawing has a diameter larger than that of the upper half in the drawing. The lower half of the rotor 26 shown in the figure gives a large rotational torque to the rotating structure 20 by the rotating magnetic flux of the stator 40. The first rotating member 22 is made of a magnetic material such as pure iron, and is configured to be substantially parallel with a gap other than the joint portion with the rotor 26 to form the passage of the rotating magnetic flux. is doing. The second rotating member 23 is made of a material having a small thermal conductivity such as an alloy of 50 wt% iron and 50 wt% nickel (TNF), and the first rotating member 22 and the third rotating member. A gap is maintained between the member 24 and other than the connecting portions. The third rotary member 24 and the rotary lid 27 are made of a material suitable for a sliding bearing such as iron alloy tool steel SKD11 (JIS standard), and the first rotary member 22 and the second rotary member 23 Between these, it is comprised without contact, maintaining a clearance gap except for the said connection part. The heat of the X-ray target 3 is conducted through the target support 21, the first rotating member 22 and the second rotating member 23 to the third rotating member 24 in which a slide bearing is formed. It has become.

The fixed structure 30 has a fixed body portion 31 at the center of the figure, an upper shoulder 31a and a small fixed body diameter part 31b at the upper end of the fixed body part 31, and an anode fixed at the lower end of the fixed body part 31 in the figure. A portion 31c is formed. A bearing disc 32 is coaxially attached to the small fixed body diameter portion 31b so as to face the upper shoulder portion 31a in the direction along the central axis CC ′. The bearing disc 32 cannot be rotated relative to the fixed body portion 31 but is attached to the small fixed body portion 31b so as to be inclined at a small angle with respect to the central axis CC ′ of the fixed body portion 31. Yes. The fixed body portion 31 and the bearing disc 32 are made of a material suitable for a sliding bearing such as SKD11. The periphery of the end of the anode fixing portion 31c is hermetically connected to the insulator portion 1b of the vacuum vessel 1 through the sealing ring 1c, and the inside is evacuated to form the vacuum space 1a. In this embodiment, the anode fixing body portion 31 and the vacuum vessel 1 are electrically separated by the insulator portion 1b and the insulator 8, and a neutral voltage grounding type high voltage power supply can be used. It is easy to use an anode grounding type power supply.

  The anode fixing bracket 7 is connected to the lower end portion of the anode fixing portion 31c on the periphery with a screw (not shown) arranged on a circumference having a large diameter, and the anode fixing bracket 7 is interposed via an insulator 8. The stator is fixed to the stator fixing bracket 9 that fixes the stator. The stator fixing fitting 9 is connected to a fitting 9a connected to the vacuum vessel 1, and the fitting 9a is connected to a vacuum vessel support fitting 9b. Since these have large rigidity and are configured to withstand a large centrifugal force, excessive stress is not generated in the insulator portion 1b and the like. These have a role as a holding mechanism of the X-ray tube, and are fixed to a storage container of a rotary anode X-ray tube (not shown) that contains insulating oil to constitute a rotary anode X-ray tube device.

  A cooling hole 31f is provided in the central portion of the fixed body portion 31 and the anode fixing bracket 7, and a cooling pipe 7a introduced from the side wall of the anode fixing bracket 7 is inserted into the cooling hole 31f. In operation, the insulating oil flowing in from the side wall side of the anode fixing bracket 7 of the cooling pipe 7a is ejected from the upper end of the cooling pipe 7a and passes between the outside of the cooling pipe 7a and the inner wall of the cooling hole 31f. It flows so as to cool the outer wall and the like of the vacuum vessel 1 through a plurality of through holes 7b provided in the side wall of the vacuum vessel 1. In this way, a bearing portion described later is sufficiently cooled.

Next, the bearing portion will be described in more detail with reference to FIG. 2 in which the main part of FIG. 1 is enlarged and displayed in cross section, and only a part of the fixed structure 30 is displayed in non-cross section. Herringbone-shaped spiral grooves GA1 and GA2 are provided on the right and left surfaces of the bearing disc 32 in the drawing, and the right surface of the bearing disc 32 has a bearing gap of about 20 μm from the left surface in the peripheral portion of the rotary lid 27. The left surface of the bearing disk 32 is opposed to the right surface of the rotating member protrusion 24c in which a part of the third rotating member 24 protrudes in an annular shape while maintaining a bearing clearance of about 20 μm. ing. Each helical groove GA1, GA2 and each bearing gap is filled with a liquid metal lubricant LM made of a gallium-indium-tin (Ga-In-Sn) alloy which is liquid during operation, Two thrust bearings BA1 and BA2 are formed that generate dynamic pressure in directions opposite to each other and along the central axis CC ′. The liquid metal lubricant LM is not shown for the sake of clarity. The illustrated left surface of the rotating body protrusion 24c and the illustrated right surface of the fixed body portion 31 are opposed to each other with a large gap of about 1 mm, and the liquid metal lubricant LM is supplied thereto. The surface of the right end portion of the fixed body small diameter portion 31b shown in the figure and the surface of the central portion of the rotary lid 27 are opposed to each other with a gap of about 0.5 mm minimum, and the liquid metal lubricant LM is supplied to the gap. .

  The fixed body portion 31 has a substantially columnar shape, and bearing grooves GR1 and GR2 including two sets of herringbone-shaped spiral grooves are provided on the outer surface of the cylindrical shape, and the axial direction is in the range of 5 to 40 μm. A bearing gap whose dimensions change with the position is maintained to face the inner surface of the third rotating member 24, and a liquid metal lubricant LM is supplied to the bearing grooves GR1, GR2 and the bearing gap. First and second radial bearings BR1 and BR2 that generate dynamic pressure in the direction are configured. An annular deep groove DR1, DR2, DR3, which is an annular deep groove, is formed in the fixed body portion 31 between the first and second radial bearings BR1, BR2 and at the respective end portions. The annular deep grooves DR1, DR2, DR3 are covered with a cylindrical inner surface of the third rotating member 24, and these are filled with a liquid metal lubricant LM to form an annular reservoir.

As shown in FIG. 2, there is a fixed body extension 31d extending from the radial bearings BR1 and BR2 at substantially the same diameter from the radial bearings BR1 and BR2 on the left side of the fixed body 31 as shown in FIG. There is a small left diameter portion 31e, and the small left diameter portion 31e is connected to the anode fixing portion 31c having a large diameter. In FIG. 2, a belt-like portion having a predetermined width, for example, 5 mm, on the surface of the fixed body extension portion 31d located on the left side of the illustrated deep wall DR3W of the annular deep groove DR3 positioned on the left side of the drawing and 0. A belt-like portion having a predetermined width, for example, 5 mm, on the surface of the third rotating member 24 facing with a minute gap of about 1 mm is a surface that is not wetted by the liquid metal lubricant LM as described above. An annular forbidden band PR1 is formed which acts to prevent the passage of the liquid metal lubricant LM due to the surface tension thereof. The gap in this portion is larger than the bearing gaps of the radial bearings BR1 and BR2, and there is no mechanical contact, but leakage of the liquid metal lubricant LM when the rotating structure 20 is stationary. The surface tension is sufficient to prevent the occurrence of the damage.

In FIG. 2, there is a spiral groove GR3 on the surface of the fixed body extension 31d located on the left side of the annular forbidden band PR1, and this surface is opposed to the surface of the third rotating member 24 with a minute gap. A portion of this is filled with the liquid metal lubricant LM and constitutes a third radial bearing BR3. Of the spiral groove GR3, the bearing groove GR3a located on the right side of the drawing is formed in a narrower range than the bearing groove GR3b located on the left side of the drawing. Therefore, when there is no additional supply of a new liquid metal lubricant LM when the rotating structure 20 is rotating, a region formed of a part of the bearing groove GR3a and the bearing groove GR3b located on the right side of the spiral groove GR3 in the drawing. Only BR3a is supplemented with the liquid metal lubricant LM. When the liquid metal lubricant LM is added to the third radial bearing BR3, a force pushing the spiral groove GR3 to the right in the drawing is generated due to an increase in pumping action in the bearing groove GR3b on the left in the drawing. In this way, the liquid metal lubricant LM is prevented from leaking through the annular forbidden band PR1. The radial load of the rotating body is substantially supported by the first and second radial bearings, and the third radial bearing only generates an auxiliary bearing force.

  In FIG. 2, a rotating annular body 28 having a surface facing the surface of the fixed body portion 31 with a clearance of about 0.1 mm is attached to the left end portion of the third rotating body member 24 with screws or the like (not shown). It has been. The rotating annular body 28 is divided into two in the longitudinal direction for easy mounting. In the rotating annular body 28, the surface of the rotating annular body 28 facing the fixed body portion 31 is a surface that is not wetted by the liquid metal lubricant LM. The surfaces of the left-side small-diameter portions 31e of the fixed body portions 31 facing each other with a gap between these surfaces are also formed so as not to get wet. Since these gaps are larger than the bearing gaps of the thrust bearings BA1 and BA2 and the first and second radial bearings BR1 and BR2, the surfaces facing each other are not mechanically contacted in any state. It has become. A spiral groove GA3 that does not generate a large pressure may be provided on the surface of the rotating annular body 28 facing the side surface of the fixed body portion 31.

Since the bearing disc 32 can be tilted with respect to the central axis CC ′ of the fixed structure 30 when the angle of the rotation center axis of the rotary structure 20 is slightly shifted, the thrust bearing BA1 and the thrust bearing BA2 Each bearing gap need not be inclined in the radial direction, and stable operation is guaranteed. This effect is obtained when the distance between the first and second radial bearings BR1 and BR2 is relatively short, or when the gap between the bearing surfaces of the first and second radial bearings BR1 and BR2 is relatively large, This is noticeable when the diameter of the thrust bearings BA1 and BA2 is relatively large. Furthermore, even if the gap between the respective bearing surfaces of the thrust bearings BA1 and BA2 is narrower than in the prior art, the bearing surfaces facing each other are always kept in parallel so that a large bearing pressure is stably generated. Therefore, since the bearing gaps of the thrust bearings BA1 and BA2 can be made narrower than in the past, the amount of movement of the rotary structure 20 in the tube axis CC ′ direction can be limited to be smaller.

  Next, with respect to the structures of the first radial bearing BR1 and the second radial bearing BR2, FIG. 3 schematically showing an enlarged part of FIG. 2 and FIG. 4 showing the dimensional relationship of the bearing gap G. Details will be described with reference to FIG. In the following description, for the sake of simplicity, the fixed body portion 31 is simply referred to as a bearing fixed body 31 and the third rotating body member 24 is simply referred to as a bearing rotating body 24. FIG. 3A schematically shows the structure and mode of the radial bearings BR1 and BR2 at the time of light load by expanding the bearing gap G in the radial direction in order to explain the present invention. FIG. 3B schematically illustrates the structure and mode of the radial bearings BR1 and BR2 under heavy load by expanding the bearing gap G in the radial direction in order to explain the present invention. FIG. 3C schematically shows a cross section of the outer surface T of the bearing fixing body 31 and the inner surface S of the bearing rotating body 24 and the bearing gap G at specific positions along the central axis CC ′ of the bearing fixing body 31. It represents. In these drawings, the outer surface T of the bearing fixing body 31 is provided with herringbone-shaped bearing grooves GR1 and GR2, which are represented only by a stripe pattern. Actually, the depth of the bearing groove is about 10 μm, and the size of the bearing gap is about 5 to 40 μm. However, the depth of the bearing grooves GR1 and GR2 is omitted, and the distribution of the size of the bearing gap G is expressed. Represents. Therefore, the outer surface T of the bearing fixed body 31 indicates the outer surface represented by extrapolating the hills of the bearing groove.

The structure of the radial bearing will be described with reference to FIG. Bearing rotating body 24 of substantially cylindrical shape on the outer periphery of the bearing fixing member 31 of approximately cylindrical shape are fitted, the bearing surface is provided on these opposing surfaces. The inner surface S of the bearing rotating body 24 is a smooth cylindrical surface, and the outer surface T of the bearing fixing body 31 is provided with bearing grooves GR1 and GR2 having a depth of about 10 μm. The gap between these bearing surfaces constitutes a bearing gap G. The bearing gap G is supplied with a liquid metal lubricant LM that is liquid at least during operation. A direction along the central axis CC ′ of the bearing fixed body 31 is a Z axis, a direction perpendicular to the Z axis is an R axis, and a rotation angle in a plane perpendicular to the Z axis is θ. In FIG. 3A, a portion from z = z1 to z = z3 constitutes a first radial bearing BR1 having a bearing width Lb1, and a portion from z = z4 to z = z6 has a bearing width Lb2. The second radial bearing BR2 is configured. There is an annular deep groove DR2 having a separation distance Lg at a position from z = z3 to z = z4 of the bearing fixed body 31, and pressure is not substantially generated in this portion.

The dimensional relationship of the bearing gap G between the radial bearings BR1 and BR2 will be described with reference to FIG. 4 shows a further enlarged cross-sectional view of the bearing gap G in FIG. 3A. The straight line S in the figure represents the inner surface S of the bearing rotating body 24, and the broken line T in the figure represents the bearing fixed body. 31 shows an outer surface T expressed by extrapolating a hill of a bearing groove on the surface of the bearing fixing body 31 in a state where the central axis CC ′ of 31 coincides with the central axis C1-C1 ′ of the bearing rotating body 24. It is . Assuming that the central axis CC ′ of the bearing fixed body 31 is the Z axis, in the drawing, a region surrounded by the cross section z = z1, the cross section z = z3, the inner surface S, and the outer surface T is the first radial bearing BR1. The area surrounded by the cross section z = z4, the cross section z = z6, the inner surface S, and the outer surface T represents the second radial bearing BR2. A region within the cross section z = z1 and sandwiched between the inner surface S and the outer surface T is a bearing gap having a bearing gap dimension G1 at the illustrated right end of the first radial bearing BR1. The bearing gap dimension G1 is, for example, about 40 μm, and is larger than the conventional uniform bearing gap dimension. The conical surface including the circle U formed by the cross section z = (z3 + z4) / 2 at the center of the annular deep groove DR2 and the inner surface S and the circle V formed by the cross section z = z1 and the outer surface T are the outer surface. Including a part of T, when the angle formed by the extended surface with the inner surface S is α, it passes through the circle U and forms an angle α with the inner surface S on the side of the cross section z = z6. Let W be the circle formed by the intersection of the conical surface and the cross section z = z6. The conical surface including the circle W and the circle U forms part of the outer surface T. A cross section z = z2 includes a circle U1 formed by a concentric cylindrical surface having a radius smaller than the radius of the inner surface S by the minimum bearing gap dimension G2 and a conical surface passing through the circle V and the circle U. Similarly, a cross section z = z5 includes a circle U2 formed by the intersection of a cylindrical surface having a radius smaller than the radius of the inner surface S by the minimum bearing gap dimension G2 and a conical surface passing through the circle W and the circle U. In this case, the angle α is the maximum inclination angle that the bearing rotating body 24 forms with respect to the bearing fixed body 31.

Therefore, the bearing clearance dimension of the first radial bearing BR1 varies linearly with the position z from the large bearing clearance dimension G1 to the minimum bearing clearance dimension G2 from z = z1 to z = z2, and z = From z2 to z = z3, a uniform bearing gap dimension G2 is maintained. Similarly, the bearing clearance dimension of the second radial bearing BR2 is maintained at a uniform bearing clearance dimension G2 from z = z4 to z = z5, and the smallest bearing from z = z5 to z = z6. The gap dimension G2 changes linearly with the position z from the large bearing gap dimension G6. Area annular deep groove DR2 is present, z = z3 from to z = z4, if separation distance Lg is located is sufficiently large to match the z2 and z3, z4 and z5, outer surface T and the inner surface There is a case where a portion where S is parallel is not generated. The separation distance Lg may be about 5 mm or may exceed 30 mm. In the portion where the angle formed by the outer surface T and the Z axis changes discontinuously, z = z2 and z = z5, rounding is preferably performed so as to change gradually.

  In fact, such a bearing can be manufactured as follows. The inner surface S of the bearing rotating body 24 is processed so as to be scraped off with a predetermined uniform radius. The bearing fixing body 31 cuts the cylindrical material along a conical surface connecting the circle V and the circle U having a predetermined radius, and then, the circle W and the circle U having the predetermined radius as described above. Are then cut so as to form a cylindrical surface that is coaxial with the conical surface, parallel to the inner surface S, and has a radius that matches the minimum bearing gap dimension G2. Made. Further, the outer surface T is finished by rounding and cutting the periphery of z = z2 and z = z5 so that the inclination of the surface is sufficiently continuous. Next, a spiral groove having a depth of about 10 μm is provided in a portion of the outer surface T between z = z1 and z = z3 and a portion of z = z4 to z = z6. The bearing gap dimension G1 is preferably about 40 μm, the bearing gap dimension G2 is about 5 μm, and the bearing gap dimension G6 is preferably about 22 μm. In this case, if the total bearing length Lt is 112 mm, the inclination angle of the rotation center axis is about 0.03 degrees or less, and when used in a CT scanner, the rotation center axis is constant during scanning at a constant speed. Therefore, it does not substantially affect the characteristics of the X-ray tube.

  The operation of the X-ray tube having the radial bearings BR1 and BR2 configured as described above will be described with reference to FIGS. 3 (a), 3 (b), 3 (c), 5 and 6. FIG. . It is assumed that the bearing rotating body 24 rotates at a predetermined rotation speed, for example, 6000 rpm, and an external force F is applied to the center of gravity GX of the entire rotating body including the X-ray target 3. When the external force F is sufficiently small, as shown in FIG. 3A, the center axis C-C 'of the bearing fixed body 31 and the center axis C1-C1' of the bearing rotating body 24 substantially coincide with each other. It is kept. In this case, the size of the bearing gap G changes in the Z-axis direction, and since the average value in the Z direction is a large value, the necessary rotational torque and bearing loss are sufficiently small values. The bearing rigidity is also set to an appropriate value.

  When the external force F is sufficiently large, the center of gravity GX is displaced in a direction that forms an angle with the direction of the external force F and tilts around the center of gravity GX. The results of calculating these states are shown in FIGS. In FIG. 5, the horizontal axis represents the amount of displacement of the center of gravity GX in the direction parallel to the external force F, and the vertical axis represents the direction perpendicular to the center axis C1-C1 ′ of the bearing rotating body 24 and the external force F. Represents the displacement of the center of gravity GX. As can be seen from FIG. 5, the displacement amount and the displacement direction of the center of gravity GX change depending on the size of the center of gravity coordinate L1. The displacement of the center of gravity GX is large when the same external force F is applied and the center of gravity coordinate L1 is small. The center of gravity coordinate L1 is the distance between both ends of the first radial bearing BR1 and the second radial bearing BR2, that is, the bearing. It becomes the minimum near the center position of the total length Lt, and becomes larger when the barycentric coordinate L1 is larger.

  In FIG. 6, the horizontal axis represents the inclination angle of the central axis C1-C1 ′ of the bearing rotating body 24 around the center of gravity GX with the direction parallel to the external force F as the center, and the vertical axis represents the center of gravity G. As shown, the inclination angle of the central axis C1-C1 ′ of the bearing rotating body 24 around the axis perpendicular to both directions of the central axis C1-C1 ′ of the bearing rotating body 24 and the external force F is shown. As can be seen from FIG. 6, the tilt angle and tilt direction of the rotation center axis C1-C1 'vary depending on the size of the barycentric coordinate L1. It can be seen that the inclination angle of the rotation center axis C1-C1 ′ is large when the center of gravity coordinate L1 is small, the center of gravity coordinate L1 is the minimum near the center position of the bearing total length Lt, and is large when the center of gravity coordinate L1 is larger. . FIG. 6 shows that the inclination of the rotation center axis C1-C1 'increases as the external force F increases regardless of the value of the center of gravity coordinate L1.

  When the external force F is increased, the center of gravity GX is displaced at an angle in the θ direction with the external force F as described above, and the rotational moment around the axis facing the external force F and the direction of the external force F are perpendicular. A rotational moment is generated around the direction-oriented shaft, the outer surface T of the bearing fixed body 31 and the inner surface S of the bearing rotating body 24 are partially close to each other, and the bearing pressure in the adjacent portion is increased and the bearing is increased. The position and inclination of the central axis C1-C1 ′ of the rotating body 24 are corrected. When the external force F further increases, the inclination angle of the bearing rotating body 24 becomes the maximum, and as shown in FIG. 3B, the inner surface S and the outer surface T are between z = z1 and z = z2. The portions are substantially parallel and the portions between z = z5 and z = z6 are substantially parallel in the opposite direction. This state is shown in cross section in FIG. In FIG. 3C, S is an inner surface of the bearing rotating body 24 when the bearing rotating body 24 is inclined with respect to the bearing fixed body 31 at a maximum inclination angle α, and S ′ is the bearing rotation. This is the inner surface of the bearing rotating body 24 when the body 24 is not inclined with respect to the bearing fixed body 31. The points A1 and A2 in FIG. 3 (c) are the circumferentially adjacent portions that are closest to the opposing surface in the circumferential direction at the axial position z = z1 and the axial position z = z2 in the first radial bearing BR1. A point on an outer surface T is represented, and the points B1 and B2 are the most opposed surfaces in the circumferential direction at the axial position z = z6 and the axial position z = z5 in the second radial bearing BR2. It represents a point on the outer surface T that is near the circumferentially adjacent portion. These points are also included in the contact portion where the gap between the opposing surfaces is substantially eliminated. The contact portions are located in the first radial bearing BR1 from the axial position z = z1 to the axial position z = z2, and in the second radial bearing BR2, the axial position z = z5 to the axial position z = z6. Extends in the axial direction. Further, the axial tangent of the inner surface S of the bearing rotating body 24 between the axial position z = z1 and the axial position z = z2 and between the axial position z = z5 and the axial position z = z6. And the axial tangent of the outer surface T of the outer surface T of the bearing rotating body 31 are substantially zero values, and are spread in the axial direction as a small inclination difference portion that is smaller than the maximum inclination angle α. . Further, the point A2 is formed so as to approach the facing surface as much as the degree at the end position z = z1 at the axial position z = z2 other than the end position z = z1 of the first radial bearing BR1. The adjacent surface portion extends in the axial direction from the axial position z = z1 to the axial position z = z2. Similarly, the point B2 is formed so as to approach the facing surface as much as the extent at the end position z = z6 at the axial position z = z5 other than the end position z = z6 of the second radial bearing BR2. The adjacent surface portion extends in the axial direction from the axial position z = z5 to the axial position z = z6.

  When the bearing rotator 24 rotates at a rotational speed of 6000 rpm and the external force F is applied and the central axis of the bearing rotator 24 is inclined, the displacement amount of the bearing rotator 24 in the cross section z = z1 and the first The relationship with the radial load capacity of the radial bearing BR1 is calculated and is shown by a curve (1) in FIG. In the vicinity of points A1 and A2 in FIG. 3C, when the bearing rotating body 24 is inclined, the difference in the distance between the opposing surfaces of the inner surface S of the bearing rotating body 24 and the outer surface T of the bearing fixed body 31 is reduced. While approaching each other. As the distance between these surfaces decreases, the pressure increases. However, when these surfaces are sufficiently close together, they are further approached while being substantially parallel, so the total pressure received by the inner surface S of the bearing rotor 24 is extremely large. Become. For comparison, FIG. 7 shows the amount of displacement at the end of the bearing rotating body 24 when a conventional bearing having the same size and a uniform bearing gap G dimension in the axial direction is used. The relationship with the radial load capacity of the radial bearing BR1 is shown by a curve (2). Curve (2) shows a case in which the size of the bearing gap G is a constant value of 15 μm in the entire region Lt of the bearing, and the bearing characteristics at low load are the same as in the case of curve (1). . In the case of the curve (2), when the bearing rotating body 24 is inclined, both bearing surfaces approach each other while increasing the angle formed between the bearing surfaces, so that the gap is narrow and the pressure is increased. The area is small, partly in mechanical contact without a sufficient increase in total pressure, and the radial load capacity is limited to a small value.

FIG. 8 shows the relationship between the rotational torque of the first radial bearing BR1 and the radial load capacity in the rotary anode X-ray tube of the present invention when the diameter of the first radial bearing BR1 is 60 mm and the bearing width Lb1 is 70 mm. Illustrated. In FIG. 8, the curve (0A), the curve (1A), the curve (2A), the curve (3A), and the curve (4A) are respectively the rotation speeds of the rotating anode of 9000 rpm, 6000 rpm, 3000 rpm, 1500 rpm, and 750 rpm. The case characteristics. Curves (0A) and (1A) have a sufficiently large radial load capacity and are scaled out in FIG. For comparison, the characteristics of the first radial bearing BR1 in a conventional X-ray tube having a bearing clearance dimension of 15 μm are illustrated from the curve (0B) to the curve (4B). In FIG. 8, the curve (0B), the curve (1B), the curve (2B), the curve (3B), and the curve (4B) indicate that the rotation speed of the rotating anode is 9000 rpm, 6000 rpm, 3000 rpm, 1500 rpm, and 750 rpm, respectively. The case characteristics. In any case, with the rotating anode X-ray tube of the present invention, the radial load capacity at high load is improved to about 7 times when the bearing characteristics at light load are equivalent to those of the conventional X-ray tube. I understand that.

  FIG. 8 shows the centrifugal force applied only to the first radial bearing BR1 when an X-ray tube having a rotating anode with a mass of approximately 15 kg of the rotating anode is attached to a rotating mount with a track radius of 74.5 cm and rotated. In this case, the time required for one rotation, that is, the scan time is described for reference. This indicates that if the present invention is applied, ultra-high speed CT with a scan time shorter than 0.2 seconds can be realized. When trying to realize a 0.17 second scan with a conventional rotating anode X-ray tube, as can be seen from FIG. 15, the size of the bearing gap G should be maintained at about 8 μm over the entire bearing length Lt, and the rotational speed should be 6000 rpm or more. It is necessary to keep the rotational torque at 0.8 N · m or more. This is extremely difficult for the reasons described above. On the other hand, if it is attempted to realize a 0.17 second scan with the rotary anode X-ray tube having the above-described structure to which the present invention is applied, the bearing gap G is set to the above dimensions and the rotation speed is as shown in FIG. The rotational torque may be maintained at about 0.6 N · m at 3000 to 6000 rpm. Since the rotational torque is smaller than that of the conventional rotary anode X-ray tube, it is natural that the rotational speed of the rotary anode X-ray tube of the present invention can be increased when the rotational torque has the same limitation. As can be seen from FIG. 8, the rotating anode X-ray tube of the present invention has a large radial load capacity even when the rotation speed is low, so that it is difficult to cause inconveniences at the start and stop of rotation and stable operation is expected. it can.

  Another embodiment will be described with reference to FIG. In FIG. 9, parts having the same functions as those in FIG. FIG. 9A schematically shows the state of the bearing rotating body 24 and the bearing fixed body 31 when the bearing rotating body 24 rotating at a predetermined rotational speed receives a light load. ) Represents a state where the bearing rotating body 24 receives a large external force and the central axis of the bearing rotating body 24 is tilted to the maximum. In this embodiment, the outer surface T of the bearing fixed body 31 is formed to have the same radius, and the inner surface S of the bearing rotating body 24 is from z = z1 to z = z2 and from z = z5 to z = z6. The angle α is formed with the outer surface T of the bearing fixed body 31 in the region up to and is inclined outward so as to have the same relative relationship as described above. The relative relationship of the bearing surfaces is the same as in the first embodiment, but the diameter of the outer surface T of the bearing fixed body 31 is constant in the direction of the central axis CC ′, and the inner surface S of the bearing rotating body 24 is It is inclined in the direction opposite to the outer surface T of the bearing fixed body 31 in the first embodiment. The relative relationship between the bearing surfaces is the same as in the case of the first embodiment and operates in the same manner, so detailed description thereof is omitted.

  Another embodiment will be described with reference to FIG. In FIG. 10, parts having the same functions as those in FIG. In this embodiment, when a very large external force is applied, the bearing rotating body 24 or the bearing fixed body 31 is deformed within a limit of elasticity, such as bending, and deformation when a rated external force is applied. The amount is determined in advance, and the outer surface T of the bearing fixed body 31 and / or the inner surface S of the bearing rotating body 24 is positioned in the axial direction so that the closest portion of the bearing surface is not localized when a rated external force is applied. This is an example in which the curve is previously curved as a function of In this case, the relative relationship between the outer surface T of the bearing fixed body 31 and the inner surface S of the bearing rotating body 24 is optimized in the state where the rated external force is applied. Thus, even when the bearing fixed body 31 or the bearing rotating body 24 is elastically deformed, a sufficiently large radial load capacity can be obtained. In order to easily realize this, it is also possible to perform a matching process as described above. Since the detailed structure and operation of the present embodiment are the same as those of the first embodiment, detailed description thereof is omitted.

  Another embodiment will be described with reference to FIG. In FIG. 11, parts having the same functions as those in FIG. In the present embodiment, the first radial bearing BR1 and the second radial bearing BR2 are configured to have substantially the same structure and substantially the same dimensions, and the center of gravity GX of the entire rotating portion of the rotating anode is obtained. This shows a state in which the radial bearings BR1 and BR2 are exactly in the middle position, that is, the position of z = (z3 + z4) / 2. In this case, the dimension of the bearing gap G is a constant value larger than 15 μm, and the rotational torque at low load is a small value. Although not shown in FIG. 6, the first radial bearing BR1 and the second radial bearing BR2 have the same dimensions, and the position of the center of gravity GX is exactly at the middle point, that is, a special case where L1 = Lt / 2 As a result of calculation in the same manner as in FIG. 6, it was obtained that the rotation center axis C1-C1 ′ was displaced in parallel with the fixed body center axis CC ′. In this case, when the external force F becomes large, the center axis C1-C1 ′ of the bearing rotating body 24 is displaced while being kept parallel to the center axis C-C ′ of the bearing fixed body 31, so It is preferable that the dimensions are substantially constant regardless of the position z. In this case, when the external force F increases, the bearing surfaces approach each other in a state where the area of the closest part is large, so that a large radial load capacity is obtained. In an actual rotating anode X-ray tube, it is difficult to position the center of gravity GX of the entire rotating portion just in the middle of the radial bearings BR1 and BR2, but this can be realized by, for example, the configuration shown in FIG. . Although it is not preferable, even if the position of the center of gravity GX does not exactly match the intermediate position, a similar effect can be obtained as long as it substantially matches. In FIG. 12, parts corresponding to those in FIG. 1 are denoted by the same reference numerals. In FIG. 12, the X-ray target 3 has a large hole in the center portion, and this hole portion is fixed to one end of the folded metal fitting 100, and the other end of the folded metal fitting 100 is fixed to the target support 21. Further, the rotating annular body 28 at the other end of the bearing rotating body 24 is made of a high-density material such as tungsten. The embodiment shown in FIG. 11 can be realized by optimizing the masses and mounting positions of the X-ray target 3 and the rotating annular body 28.

Although the invention has been described with reference to embodiments and examples, the invention is not limited to the embodiments and examples illustrated herein, and various modifications can be made without departing from the spirit and scope of the invention. It should be understood that various embodiments are possible and that various changes and modifications can be made. For example, in the structure shown in FIG. 1, the position of the center of gravity GX of the entire rotating part may be on the opposite side of the position of z = z3 from the position of z = z1 in FIG. It may be in a position between the position and z = z3. Although not preferred, the same effect can be obtained by forming a single radial bearing and inclining the bearing clearance dimension in the direction of the central axis in the opposite direction to each other within the single radial bearing. I can do it. Further, as shown in FIG. 9, the surface of the rotating body may be inclined in one radial bearing, and the surface of the stationary body may be inclined in the other radial bearing as shown in FIG. . A bearing fixed body cylindrical, the bearing rotating body is also included in the present invention be those fitted to the cylindrical therein it is natural. In FIG. 1 and FIG. 2, the bearing rotating body 32 constituting the thrust bearing may naturally be fixed to the bearing fixing body 31. Of course, the shape of the bearing groove, the angle of the bearing groove, and the like may be changed in various ways. In the present invention, “rotating body” is a general term for rotating parts and represents a concept including “bearing rotating body” and the like. Similarly, “fixed body” is a general term for parts that do not rotate, and represents a concept including “bearing fixed body” and the like. In the present invention, the “bearing surface” represents a surface on which the bearing surface is provided and the surface of the hill of the bearing groove is extrapolated, and the “bearing clearance” refers to a region in the bearing sandwiched between the opposing bearing surfaces. The “bearing gap dimension” or “bearing gap dimension” represents a value obtained by averaging the radial differences between the bearing surfaces in the circumferential direction.

  The rotary anode type X-ray tube and rotary anode type X-ray tube apparatus of the present invention can be effectively used as an X-ray generation source for an X-ray CT scanner and other radiation equipment. In particular, since the radial bearing can obtain an extremely large radial load capacity, it is suitable for an X-ray tube apparatus for a high-speed scanning X-ray CT scanner that has a large anode heat capacity and is revolved at a high speed. In this type of rotary anode X-ray tube that has been reported in the past, it is necessary to narrow the bearing gap in order to obtain a large radial load capacity, and accordingly, a large rotational torque is required. Although it could not be put into practical use because it was necessary to maintain high-precision dimensions, the rotary anode X-ray tube of the present invention can obtain a large radial load capacity with a small rotational torque and maintain high precision. Since it is not necessary, it can be sufficiently put into practical use as the X-ray tube apparatus for the high-speed scanning X-ray CT scanner. The inclination angle of the rotation center shaft at high load is limited to a sufficiently small value and does not cause a problem in actual use. In addition, the bearing gap has a large size outside a specific limited range, and deformation of the bearing is allowed, so it is inexpensive, highly reliable, has a very large capacity, and can withstand extremely large centrifugal acceleration. In addition, it is possible to provide a rotary anode type X-ray tube and to shorten the scanning time of the ultra-high speed scanning CT scanner, and thus the industrial utility value is high.

It is a longitudinal cross-sectional view which shows a part of rotary anode type X-ray tube apparatus concerning this invention. It is a fragmentary longitudinal cross-section which shows a part of rotation mechanism used for the rotating anode type | mold X-ray tube concerning this invention. FIG. 2 is a partial longitudinal sectional view and a transverse sectional view schematically showing a part of a rotating mechanism used in a rotating anode type X-ray tube according to the present invention. It is drawing for demonstrating the structure of the radial bearing used for the rotating anode type | mold X-ray tube concerning this invention. It is a characteristic view for demonstrating operation | movement of the principal part of the rotating anode type | mold X-ray tube concerning this invention. It is a characteristic view for demonstrating operation | movement of the principal part of the rotating anode type | mold X-ray tube concerning this invention. It is a figure showing the characteristic of the radial bearing used for the rotating anode type X-ray tube concerning this invention. It is a figure showing the characteristic of the radial bearing used for the rotating anode type X-ray tube concerning this invention. It is a fragmentary longitudinal cross-sectional view which represents typically the other Example of the rotating anode type X-ray tube concerning this invention. FIG. 6 is a partial longitudinal sectional view schematically showing still another embodiment of the rotary anode type X-ray tube according to the present invention. FIG. 6 is a partial longitudinal sectional view schematically showing still another embodiment of the rotary anode type X-ray tube according to the present invention. It is a longitudinal cross-sectional view which shows a part of other Example of the rotating anode type X-ray tube apparatus concerning this invention. It is the figure which shows the fragmentary longitudinal cross-section which shows the structure of the principal part of the conventional rotary anode type | mold X-ray tube, and a characteristic. It is a fragmentary longitudinal cross-sectional view which represents typically the structure and aspect of the principal part of the conventional rotating anode type | mold X-ray tube. It is a characteristic view for demonstrating operation | movement of the principal part of the conventional rotary anode type | mold X-ray tube. It is a characteristic view for demonstrating operation | movement of the principal part of the conventional rotary anode type | mold X-ray tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum container 1a Internal space 2 Cathode 3 X-ray target 4 X-ray irradiation window 5 Anode fixing screw 6 Shielding cylinder
10 rotation mechanism
20 Rotating Structure 21 Target Support Body 22 First Rotating Body Member 22a Rotating Body One End 22b Rotating Body Other End 23 Second Rotating Body Member 23a Rotating Body One End 23b Rotating Body Other End 24 Third Rotating Body Member (bearing rotating body)
24a Rotating body part 24b Rotating body diameter small portion 24c Rotating body projecting portion 26 Rotor 27 Rotating lid 28 Rotating annular body
30 fixed structure 31 fixed body part (bearing fixed body)
31a Upper shoulder portion 31b Small fixed body diameter portion 31c Anode fixed portion 31d Fixed body extended portion 31e Small left diameter portion 31f Cooling hole 32 Bearing disc 40 Stator BA1 Thrust bearing BA2 Thrust bearing BR1 First radial bearing BR2 Second Radial bearing BR3 Third radial bearing BR3a Third radial bearing region DR1 Annular deep groove DR2 Annular deep groove DR3 Annular deep groove DR3W Annular deep groove DR3 left wall shown in the figure
F external force
G Bearing clearance
G1 to G6 Bearing clearance dimensions GA1 Thrust bearing groove GA2 Thrust bearing groove GR1 Radial bearing groove GR2 Radial bearing groove GR3 Radial bearing groove GR3a Radial bearing groove GR3b Radial bearing groove
Lb1 Bearing width
Lb2 Bearing width
Lg Width of low pressure area (separation distance)
Lt Bearing total length LM Liquid metal lubricant PR1 Annular forbidden band S Inner surface of bearing rotating body T Outer surface of bearing fixing body GX Center of gravity of rotating anode 1001 Bearing rotating body 1002 Bearing fixing body 1003 Bearing groove 1004 Bearing gap 1005 First Radial bearing 1006 second radial bearing 1007 external force 1008 central axis of bearing rotating body 1009 central axis of bearing fixed body 1011 pressure distribution 1012 pressure distribution 1021 thrust bearing 1022 thrust bearing

Claims (18)

A vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having a portion fitted coaxially with the fixed body, and an X-ray target attached to the rotating body, A rotary anode type X-ray tube substantially supporting the rotary body, wherein at least one of the radial bearings is provided on the first surface of the fixed body and the first surface. A second surface of the rotating body facing with a minute bearing gap, a spiral groove provided on at least one of the first surface and the second surface, and liquid metal lubrication filled therein And the first surface and / or the second surface is a maximum within an allowable range in which the rotating body forms an inclination angle with respect to the fixed body. At the same axial position when tilted to the limit. The circumferentially adjacent portion that is closest to the facing surface in the circumferential direction is formed to include a contact portion that substantially eliminates the gap between the facing surfaces, and the contact portion is continuously or intermittently formed. , Spread axially over a predetermined width ,
In any of the hydrodynamic slide bearings, the bearing gap has a first bearing gap dimension at the extreme end position, and a second dimension smaller than the first bearing gap at a position other than the extreme end position. The bearing clearance dimension is configured such that the bearing clearance dimension changes with the axial position between the first bearing clearance dimension and the second bearing clearance dimension at an intermediate position between them. rotating anode X-ray tube, characterized in that is. A vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having a portion fitted coaxially with the fixed body, and an X-ray target attached to the rotating body, A rotary anode type X-ray tube substantially supporting the rotary body, wherein at least one of the radial bearings is provided on the first surface of the fixed body and the first surface. A second surface of the rotating body facing with a minute bearing gap, a spiral groove provided on at least one of the first surface and the second surface, and liquid metal lubrication filled therein And the first surface and / or the second surface is a maximum within an allowable range in which the rotating body forms an inclination angle with respect to the fixed body. The fixed body and the rotation when tilted to the limit The tangent lines at the same axial position of the first intersection line and the second intersection line formed by the cross-section including the inclination angle intersecting the first surface and the second surface, respectively, are formed. It includes a small inclination difference portion formed so that an angle between tangents is smaller than the inclination angle, and this small inclination difference portion spreads over a predetermined width in the axial direction continuously or intermittently. And
In any of the hydrodynamic slide bearings, the bearing gap has a first bearing gap dimension at the extreme end position, and a second dimension smaller than the first bearing gap at a position other than the extreme end position. The bearing clearance dimension is configured such that the bearing clearance dimension changes with the axial position between the first bearing clearance dimension and the second bearing clearance dimension at an intermediate position between them. rotating anode X-ray tube, characterized in that is. A vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having the fixed body and coaxially fitted portion, and the X-ray target which is attached to the rotary member A rotary anode type X-ray tube substantially supporting the rotary body, wherein at least one of the radial bearings is provided on the first surface of the fixed body and the first surface. A second surface of the rotating body facing with a minute bearing gap, a spiral groove provided on at least one of the first surface and the second surface, and liquid metal lubrication filled therein And the first surface and / or the second surface is a maximum within an allowable range in which the rotating body forms an inclination angle with respect to the fixed body. Of the hydrodynamic slide bearing It includes a proximity surface portion formed so as to approach the facing surface at an axial position other than the end position so as to approach the facing surface at a level equal to or greater than the extent at the extreme end position, and the proximity surface portion is continuous or intermittent. In particular, the rotary anode X-ray tube is characterized by spreading over a predetermined width in the axial direction.   The first surface and / or the second surface includes a central axis of the rotating body of the fixed body and the rotating body when the rotating body is positioned coaxially with respect to the fixed body, The first and second intersecting lines that are formed on the same side with respect to the central axis crossing the first surface and the second surface, respectively, are the hydrodynamic slide bearing 1 If there are a plurality of hydrodynamic slide bearings in the vicinity of both ends, in the case of a plurality of pieces, in the vicinity of both ends on the side away from each other, The rotary anode type X according to any one of claims 1 to 3, further comprising a surface portion formed so as to be relatively widened toward each of the extreme ends along the surface. Wire tube. In any of the hydrodynamic slide bearings, the bearing gap has a first bearing gap dimension at the extreme end position, and a second dimension smaller than the first bearing gap at a position other than the extreme end position. The bearing clearance dimension is configured such that the bearing clearance dimension changes with the axial position between the first bearing clearance dimension and the second bearing clearance dimension at an intermediate position between them. The rotary anode type X-ray tube according to claim 3 , wherein Any of the hydrodynamic slide bearings includes a portion configured such that the bearing gap is substantially maintained in the second bearing gap dimension and continues over a predetermined width in the bearing width direction. claim 1, wherein, according to claim 2, rotating anode X-ray tube as claimed in any one of claims 5.   Including first and second radial bearings composed of the hydrodynamic slide bearing, and the axial direction of the first and second radial bearings when the rotating body is positioned coaxially with respect to the fixed body. The dimension of the bearing gap in the region located on the far side of each radial bearing is larger than the size of the bearing gap in the region located on the side closer to each other. 4. The method according to claim 1, wherein the first surface and / or the second surface are formed at least partially so as to increase sequentially with an axial position. The rotating anode type X-ray tube described in the item.   The first and second radial bearings including the hydrodynamic slide bearing are included, and the first surface and / or the second surface constituting the first radial bearing are arranged on a central axis of the fixed body. On the other hand, at least one of the contact portion, the small inclination difference portion, or the proximity surface portion is included on one side, and the first surface and / or the second surface constituting the second radial bearing is included. The surface includes at least one of the contact portion, the small inclination difference portion, or the proximity surface portion on a side opposite to the central axis of the fixed body. The rotary anode type X-ray tube described in any one of the above. First and second radial bearings comprising the hydrodynamic slide bearings are included, and each of the bearings includes the first and second radial bearings when the rotating body is positioned coaxially with respect to the fixed body. located in the region where the radial bearing is axially adjacent to each other, wherein at one end of the first radial bearing, of the person who is fitted inside with one of the fixed body or the rotating body, the outer surface diameter, at the other end portion of said first radial bearing, of who the is fitted inwardly of the fixed body or the rotating body, larger than the diameter of the outer surface, located in the adjacent area, the second at one end of the radial bearing of the person that is fitted to the inside in one of the fixed body or the rotating body, the diameter of the outer surface, the other end of the second radial bearing, the fixed body or the on the inside in one of the rotating body Of people who have cases, greater than the diameter of the outer surface, and the inner surface towards said fitted and outwardly of the rotating body or the fixed body having an outer surface and not parallel portion facing thereto The rotary anode type X-ray tube according to any one of claims 1 to 3, wherein the rotary anode type X-ray tube is configured as described above. First and second radial bearings comprising the hydrodynamic slide bearings are included, and each of the bearings includes the first and second radial bearings when the rotating body is positioned coaxially with respect to the fixed body. located in the region where the radial bearing is axially adjacent to one another, at one end portion of said first radial bearing, of who the is fitted to the outside among the rotating body or the fixed body, the diameter of the inner surface, at the other end portion of said first radial bearing, the rotary body or the person who has been fitted to the outside among the fixed body, smaller than the diameter of the inner surface, located on the adjacent region, the second at one end of the radial bearing of the rotary body or the person who has been fitted to the outside among the fixed body, the diameter of the inner surface, at the other end of the second radial bearing, the rotary member or said on the outside in one of the fixed body Of people who have cases, smaller than the diameter of the inner surface and the outer surface of the person who has been fitted to the inside in one of the fixed body or the rotating body having an inner surface and not parallel portion facing thereto The rotary anode type X-ray tube according to any one of claims 1 to 3, wherein the rotary anode type X-ray tube is configured as described above.   First and second radial bearings including the hydrodynamic slide bearing are included, and each of these bearings is the same as the first radial bearing when the rotating body is positioned coaxially with respect to the fixed body. From the circle formed by the central cross section perpendicular to the central axis of the fixed body at the center in the axial direction of the region sandwiched between the second radial bearing and the second radial bearing intersecting the second surface or its extended surface, The first surface is at least so that an end cross-section perpendicular to the central axis at the far end of the radial bearing substantially conforms to a conical surface that can be expected to intersect with the first surface. Ends orthogonal to the central axis at the far end of each radial bearing from the circle formed by the partial cross section or the central surface intersecting the first surface or its extended surface The second surface is formed at least partially so that a cross-section substantially conforms to a conical surface that can be expected to form a circle that intersects with the second surface. The rotating anode X-ray tube according to any one of claims 1 to 10. A vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having the fixed body and coaxially fitted portion, and the X-ray target which is attached to the rotary member A rotary anode type X-ray tube having substantially the first and second radial bearings for substantially supporting the rotary body, wherein each of the first and second radial bearings is a first of the fixed body. The second surface of the rotating body facing the first surface with a minute bearing gap, and a spiral groove provided on at least one of the first surface and the second surface And a hydrodynamic slide bearing containing a liquid metal lubricant filled therein, and each of the rotating bodies rotates when the central axis thereof substantially coincides with the central axis of the fixed body. The pressure generated in the bearing clearance of radial bearings Each of the bearings is configured to be distributed at the maximum in the central portion of each bearing, and the center of gravity of the entire rotating portion including the rotating body is the center position in the axial direction of the first radial bearing. A rotary anode X-ray tube configured to be positioned in an axial region sandwiched between axially central positions of the second radial bearing. A vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having the fixed body and coaxially fitted portion, and the X-ray target which is attached to the rotary member A rotary anode type X-ray tube having substantially the first and second radial bearings for substantially supporting the rotary body, wherein each of the first and second radial bearings is a first of the fixed body. The second surface of the rotating body facing the first surface with a minute bearing gap, and a spiral groove provided on at least one of the first surface and the second surface A hydrodynamic slide bearing containing a liquid metal lubricant filled therein, and the diameter and bearing width of the first radial bearing and the diameter and bearing width of the second radial bearing are substantially the same. The same, including the rotating body Rotating anode X-ray tube, characterized by being configured to lie in a substantially central position in the axial direction between the rolling center of gravity of the whole portion between the first radial bearing and the second radial bearing.   A value obtained by averaging the dimension of the bearing gap corresponding to each axial position of each radial bearing including the hydrodynamic slide bearing in the axial direction over the entire width of each bearing width is larger than 15 μm. The rotary anode type X-ray tube according to any one of claims 1 to 13.   2. A depth dimension of a bearing groove constituting each of the radial bearings composed of the hydrodynamic slide bearing is not less than a minimum value of a bearing gap dimension and not more than a maximum value of the bearing gap dimension. The rotary anode type X-ray tube according to any one of claims 14 to 14. A vacuum vessel defining a vacuum space, a fixed body provided in the vacuum vessel, a rotating body having the fixed body and coaxially fitted portion, and the X-ray target which is attached to the rotary member In the method of manufacturing a rotary anode X-ray tube, comprising: a hydrodynamic slide bearing using a liquid metal as a lubricant, and at least one radial bearing substantially supporting the rotary body. maximum to have a first surface, said rotary body to have a second surface, said rotary member at an inclined angle to fit in as normal to the fixed body within a tolerance In the case of tilting to the limit, the cross section including the tilt angle of the fixed body and the rotating body of the first intersecting line and the second intersecting line formed by intersecting the first surface and the second surface, respectively. , Each at the same axial position A small inclination difference portion in which an angle between tangent lines formed by the lines becomes smaller than the inclination angle is generated, and the small inclination difference portion is continuously or intermittently spread over a predetermined width in the axial direction. A step of processing the fixed body and / or the rotating body, a step of forming a spiral groove on the first surface of the fixed body or the second surface of the rotating body, and fitting the fixed body and the rotating body method of manufacturing a rotating anode X-ray tube, characterized in that it comprises a step of supplying the liquid metal lubricant in the gap formed by being sandwiched between the when case.   A rotary anode X-ray tube according to any one of claims 1 to 15, or a rotary anode X-ray tube manufactured by the method according to claim 16, and the rotary anode X-ray tube stored therein Storage container, a holding mechanism for fixing the rotary anode X-ray tube to the storage container, and rotation of the rotary anode X-ray tube from the outside of the vacuum container to the rotating body in the rotary anode X-ray tube A rotary anode X-ray tube apparatus comprising: a stator for applying torque; and means for supplying a negative high voltage to a cathode that emits electrons in the rotary anode X-ray tube.   A rotating anode X-ray tube according to any one of claims 1 to 15, a rotating anode X-ray tube manufactured by the method according to claim 16, or a rotating anode X according to claim 17. X-ray tube device, a rotating gantry that can be rotated around the central axis by mounting the same, a fixed gantry that rotatably supports the rotating gantry, and the rotary anode X-ray tube or the rotary anode X-ray tube device An X-ray detector that detects X-rays emitted from and transmitted through the irradiated object, and a device that displays a cross-section of the irradiated object using an output of the X-ray detector. X-ray CT scanner.

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