JP7070976B2 - Plain bearing structure and rotating anode X-ray tube using this bearing structure - Google Patents

Description

Embodiments of this application relate to a plain bearing structure and a rotating anode X-ray tube using this bearing structure.

X-ray systems are used in many applications such as medical CT equipment (diagnosis / treatment), industrial nondestructive inspection, and material analysis. The X-ray tube used in the X-ray system is configured to generate X-rays by colliding an electron beam from a cathode filament with an anode target.

There is a type of X-ray tube that generates X-rays by colliding an electron beam with a rotating anode target, and a plain bearing (usually a dynamic pressure bearing) is used as a bearing that pivotally supports this rotating anode target. There is. The inside of the X-ray tube has a high vacuum so as not to hinder the traveling of the electron beam, and the temperature near the electron beam collision portion of the rotating anode target becomes several thousand degrees. The heat of the rotating anode target, which has become hot in the vacuum, is radiated as radiant heat and also radiated to the slide bearing side via the structural member of the rotating anode. This prevents the rotating anode target from being damaged by high heat.

As a specific example of a rotating anode X-ray tube having a slide bearing, there is, for example, a rotating anode X-ray tube having a high cooling structure as described in Patent Document 1. In this rotating anode X-ray tube, the rotating anode target 15 is directly connected to a rotating body (a seal that rotates integrally with the motor rotor 20) 21 without a heat insulating structure. Specifically, a non-insulating liquid metal (lubricant for a dynamic pressure plain bearing) is deployed between the rotating body 21 and the fixed shaft 13 that supports the sliding shaft, and a cooling hole (cooling hole (cooling hole) is provided in the fixed shaft 13. A flow path 30 and a cooling layer 31) are provided. The structure is such that the target 15 is directly cooled via the slide bearing by the refrigerant passing through the cooling holes. Due to this cooling structure, a much higher anode cooling rate than cooling by heat radiation alone is obtained.

Japanese Unexamined Patent Publication No. 2011-60517

However, in the structure of Patent Document 1, since the rotating anode target 15 having a high temperature is directly bonded to the rotating body 21, there is a problem that the rotating body 21 is deformed by the thermal stress of the rotating anode target 15. That is, the thermal stress of the target 15 widens the inner diameter of the bearing of the rotating body 21 in the vicinity of the target, and the bearing gap becomes non-uniform. Then, the eccentricity of the portion where the bearing gap is widened becomes large, and due to the eccentricity, the bearing surface inside the rotating body 21 rotating at high speed comes into vibration contact with the fixed shaft 13. As a result, the G resistance performance of the bearing deteriorates.

As one solution to the deterioration of G-resistant performance, a method of separating the bearing surface from the target and arranging the bearing surface at a position not affected by thermal deformation can be considered. However, in this case, since the cooling performance of the target via the bearing surface is lowered, thermal deformation of the rotating body 21 is more likely to occur. When the thermally deformed rotating body 21 rotates at high speed together with the anode target 15, the vibration accompanying the rotation increases, and the load on the slide bearing increases. Then, the slide bearing is required to be able to maintain a sufficient load capacity even if the rotating body 21 is thermally deformed.

On the other hand, in the slide bearing, when the fixed shaft is viewed horizontally, grooves (grooves) for scraping liquid metal (lubricating material that easily conducts heat) are placed at the left and right positions of the fixed shaft in the axial length direction. Some have a plain surface that receives a load in the middle of the left and right grooves. The plain bearing portion is composed of two independent portions separated from each other on the left and right in the axial length direction, and the rotating body is pivotally supported from the left and right by the two separated sliding bearing surfaces. This enables stable rotation of the anode target attached to the rotating body.

At this time, the groove pattern provided on each of the two slide bearings is symmetrical and has the same shape on the left and right sides of the plane surface to which the load is applied (see the groove 34 shown in FIG. 2 of Patent Document 1). As a result, the amount of liquid metal scraped into the groove that rotates with the fixed shaft is the same on the left and right, and the liquid metal is not unevenly distributed in the bearing without causing a pressure difference between the left and right.

In this case, since the liquid metal is squeezed into the groove at a symmetrical position on the plane surface of the rotating anode target that receives the load, the plane surface that receives the load cannot be sufficiently separated from the anode target. That is, in this structure, it is difficult to cope with the deterioration of the G resistance performance due to the thermal deformation of the rotating body due to the heat from the anode target.

In summary, in a conventional plain bearing in which a groove is formed at symmetrical positions on a plane surface that receives a load, the plane surface cannot be separated from the anode target, and it is difficult to cope with a decrease in G resistance performance.

The plain bearing structure (FIGS. 1 to 8) according to the embodiment includes a shaft (112) and a plain bearing (110) that rotatably supports a target (106) having a temperature higher than that of the shaft on the shaft. The slide bearing (110) is composed of a plurality of bearing portions (110a, 110b) having a plurality of groove patterns (L1a, L1b; L2a, L2b) in the axial length direction of the shaft (112).

One of the bearing portions (eg 110a) includes an outer groove pattern (L1a) and an inner groove pattern (L1b) in the axial length direction of the shaft (112), and a plane portion (L1c) is provided between these groove patterns. including.

When viewed in the axial length direction of the shaft (112), the width of the inner groove pattern (L1b) is larger than the width of the outer groove pattern (L1a), and the position of the inner groove pattern (L1b) is the outer groove. It is closer to the target (106) than the position of the pattern (L1a).

In this plain bearing structure, the position of the plane portion (L1c) is configured to be at a position farther (for example, D1a away) from the position of the inner groove pattern (L1b) with respect to the target (106). ..

That is, the position of the plane portion (L1c) deviates from the high temperature target (106) by the amount of the wide inner groove pattern (L1b) intervening. Then, the plane portion (L1c) that receives the load of the rotating target (106) is less likely to receive the thermal stress of the target (106), and it becomes easier to cope with the deterioration of the G resistance performance due to the thermal deformation.

FIG. 1 is a partial cross-sectional view illustrating an example of the internal structure of an X-ray tube according to an embodiment. FIG. 2 is a partial cross-sectional view showing a portion of the rotary anode target 106 and the slide bearing 110 taken out from the X-ray tube of FIG. FIG. 3 is a diagram schematically illustrating the configuration of the slide bearing 110 of FIG. 1 or FIG. FIG. 4 is a diagram illustrating an example of the relationship between the slide bearing structure of FIG. 3 and the rotary anode target 106 of FIG. 1 or 2 (part 1: an example in which the target 106 partially faces the bearing 110b). FIG. 5 is a diagram illustrating a modified example of FIG. 4 (difference in angle of groove pattern). FIG. 6 is a diagram illustrating an example of the relationship between the slide bearing structure of FIG. 3 and the rotary anode target 106 of FIG. 1 or 2 (No. 2: Example of the target 106 not facing the bearing 110b). FIG. 7 is a diagram illustrating a comparative example (difference in width of the groove pattern) of FIG. FIG. 8 is a partial cross-sectional view illustrating an example of the internal structure of the X-ray tube according to another embodiment.

Hereinafter, the X-ray tube apparatus according to the embodiment will be described with reference to the drawings. It should be noted that the numerical values given in the following description are merely examples and do not constrain the embodiment of the present application.

FIG. 1 is a partial cross-sectional view illustrating an example of the internal structure of the X-ray tube 100 according to the embodiment. The X-ray tube 100 includes a vacuum container 102 (the degree of vacuum is, for example, about ^10-5 to ^10-6 Pa), an electron gun 104, a motor stator 111, and a motor rotor 115. The electron gun 104 functions as a cathode that generates an electron beam. A slide bearing 110 and a rotating anode target 106 are provided in the vacuum vessel 102. The rotating anode target 106 is integrally formed with the bearing rotating portion 113 and is located on the outer peripheral surface side of the bearing rotating portion 113. For example, the rotating anode target 106 is joined to the outer peripheral surface of the bearing rotating portion 113. The rotary anode target 106 is rotatably supported by a bearing rotating portion 113 inserted through a shaft (fixed shaft) 112 of the slide bearing 110.

The rotary anode target 106 is rotationally driven by a motor rotor 115 that is rotated by a rotating magnetic field from a motor stator 111 built in an X-ray tube 100. When a high frequency drive of, for example, 180 Hz is performed on the rotating anode target 106 by the rotating magnetic field, G (centrifugal acceleration) of, for example, about 70 G may be generated in the slide bearing 110. The slide bearing structure according to the embodiment (details will be described later with reference to FIG. 3 and the like) is also considered to cope with such a high G.

X-rays are output by colliding the electron beam from the electron gun 104 with the rotationally driven anode target 106. The heat of the anode target 106, which has become high temperature (the beam collision point is locally several thousand ° C) due to the collision of the electron beam, is dissipated as radiant heat and the temperature is relatively low (for example, 100 to 300 ° C). The heat is dissipated to the bearing 110 side.

FIG. 2 is a partial cross-sectional view showing a portion of the rotary anode target 106 and the slide bearing 110 taken out from the X-ray tube 100 of FIG. Further, FIG. 3 is a diagram schematically illustrating the configuration of the slide bearing 110 of FIG. 1 or FIG.

The slide bearing portions 110a and 110b are formed on the shaft 112 of the slide bearing 110. A pair of groove patterns (L1a, L1b; L2a, L2b in FIG. 3) having different grooving directions are formed on the surfaces of the slide bearing portions 110a and 110b. The liquid metal LM as a lubricant having thermal conductivity is squeezed into the plurality of grooves of these groove patterns.

As the liquid metal LM, a GaIn (gallium / indium) alloy or a GaInSn (gallium / indium / tin) alloy can be used. As this liquid metal LM, one having a viscosity of about 10 ^-3 Pa · s can be used in a state where the slide bearing 110 is not rotating.

For example, specific examples of GaInSn alloys include eutectic alloys of 68.5% gallium, 21.5% indium, and 10% tin, which are liquid at room temperature. This GaInSn alloy has high wettability and adhesion to many materials. Examples of its physical characteristics include:
Boiling point:> 1300 ° C
Melting point: -19 ° C
Relative density: 6.44 g / cm ³
Viscosity: 0.0024 Pa · s (at 20 ° C)
Thermal conductivity: 16.5 W ・ m ^-1・ K ^-1
A plain portion 110c is formed between the slide bearing portion 110a and the slide bearing portion 110b, each of which has a groove pattern (L1a, L1b; L2a, L2b in FIG. 3 and the like). The gap g2 between the surface of the plane portion 110c and the inner peripheral surface of the bearing rotating portion 113 is larger than the gap between the surface of the sliding bearing portion 110a and the inner peripheral surface of the bearing rotating portion 113, and is larger than the gap between the surface of the sliding bearing portion 110a and the inner peripheral surface of the bearing rotating portion 113. It is larger than the gap between the surface and the inner peripheral surface of the bearing rotating portion 113.

As shown in FIG. 3, the gap g2 (for example, about 100 μm) is the gap g1 (for example, about 10 μm) and the slide bearing portion between the surface of the plane portion L1c of the slide bearing portion 110a and the inner peripheral surface of the bearing rotating portion 113. It is larger than the gap g1 (for example, about 10 μm) between the surface of the plane portion L2c of 110b and the inner peripheral surface of the bearing rotating portion 113. Therefore, even if the bearing rotating portion 113 is slightly thermally deformed by the heat from the rotating anode target 106 to cause eccentricity, the inner surface of the rotating portion 113 rotating with eccentricity (for example, maximum 90 μm or less) comes into contact with the plane portion 110c. Can be prevented. From this, the G resistance performance of the slide bearing 110 can be improved.

FIG. 4 is a diagram illustrating an example of the relationship between the slide bearing structure of FIG. 3 and the rotary anode target 106 of FIG. 1 or 2 (part 1: an example in which the target 106 partially faces the bearing 110b). In FIG. 4, the width (La1; for example, 10 mm) of the plane portion area including the center of gravity G of the rotating anode target 106 on the surface of the shaft 112 is made smaller than the thickness (for example, 15 mm) of the rotating anode target 106. This allows the rotating anode target 106 to partially overlap the inner groove pattern L2b. Through this overlap portion, heat from the rotary anode target 106 can be efficiently dissipated to the shaft 112 side of the slide bearing 110.

In the embodiments after FIG. 4, in the surface of the shaft 112, a gap (corresponding to 110c in FIGS. 1 to 3) existing in the area including the center of gravity G of the rotating anode target 106 (area of width La1: corresponding to 110c in FIGS. 1 to 3) (FIG. 3). G2: for example 100 μm) can be made larger than the gap (g1: for example 10 μm in FIG. 3) existing in one (or both) of the plurality of bearing portions (110a, 110b) constituting the slide bearing 110. .. Then, even if some eccentricity occurs due to thermal deformation in the rotating portion (113 in FIG. 1 or 2) around the plane portion 110c, the inner surface of the rotating portion eccentric to the plane portion 110c does not directly collide with the load bearing capacity of that portion. It is possible to prevent deterioration of ability.

Applying a mechanical numerical example of the slide bearing 110 according to the embodiment to FIG. 4, for example, it is as follows. First, it is assumed that the shaft diameter (Φ in FIG. 3) of the slide bearing 110 portion is 40 mm so that the overall size can be imagined.

The plain bearing 110 includes a first plain bearing portion 110a and a second plain bearing portion 110b. The first slide bearing portion 110a includes a first outer groove pattern L1a (for example, width 5 mm) and a first inner groove pattern L1b (for example, width 10 mm) in the axial length direction of the shaft 112, and is between these groove patterns. Includes the first plane portion L1c (for example, width 6 mm).

The second slide bearing portion 110b includes a second outer groove pattern L2a (for example, width 8 mm) and a second inner groove pattern L2b (for example, width 16 mm) in the axial length direction of the shaft 112, and is between these groove patterns. Includes a second plane portion L2c (eg, width 6 mm).

When viewed in the axial length direction of the shaft 112, the width (10 mm) of the first inner groove pattern L1b is larger than the width (5 mm) of the first outer groove pattern L1a, and the width of the second inner groove pattern L2b ( 16 mm) is larger than the width (8 mm) of the second outer groove pattern L2a.

When viewed in the axial length direction of the shaft 112, the position of the first inner groove pattern L1b is closer to the rotating anode target 106 than the position of the first outer groove pattern L1a, and the second inner groove pattern The position of L2b is closer to the rotating anode target 106 than the position of the second outer groove pattern L2a.

The position of the first plane portion L1c is at a position (distance D1a) away from the position of the first inner groove pattern L1b when viewed from the rotating anode target 106, and the position of the second plane portion L2c is from the rotating anode target 106. It is located at a position farther (distance D2a) than the position of the second inner groove pattern L2b. Here, the distance D1a is the distance from the end of the rotating anode target 106 on the first plane portion L1c side to the central position of the first plane portion L1c in the axial length direction of the shaft 112. The distance D2a is the distance from the end of the rotating anode target 106 on the second plane portion L2c side to the central position of the second plane portion L2c in the axial length direction of the shaft 112.

When viewed in the axial length direction of the shaft 112, the center of gravity G of the rotating anode target 106 is configured to be between the first inner groove pattern L1b and the second inner groove pattern L2b. In the slide bearing 110, the load that pivotally supports the rotary anode target 106 is distributed to the slide bearing portions 110a and 110b arranged apart from each other on the left and right sides of the center of gravity G.

The first outer groove pattern L1a is a plurality of parallel grooves having a first angle θ1a (for example, 65 °) in the first rotation direction (counterclockwise) with respect to the axis perpendicular to the axial length direction of the shaft 112. The first inner groove pattern L1b is configured and has a second angle θ1b (clockwise) in the second rotation direction (clockwise) opposite to the first rotation direction with respect to the axis perpendicular to the axial length direction of the shaft 112. It is composed of a plurality of parallel grooves having (for example, 30 °).

Similarly, the second inner groove pattern L2b has a plurality of third angles θ2b (for example, 30 °) in the first rotation direction (counterclockwise) with respect to the axis perpendicular to the axial length direction of the shaft 112. The second outer groove pattern L2a, which is composed of parallel grooves, has a fourth angle θ2a (for example, 65 °) in the second rotation direction (clockwise) with respect to the axis perpendicular to the axial length direction of the shaft 112. It is composed of multiple parallel grooves.

In this embodiment, the groove angle (θ1a, θ2a) of the narrow outer groove pattern (L1a, L2a) away from the target 106 is set to the groove angle (θ1b) of the wide inner groove pattern (L1b, L2b) close to the target 106. , Θ2b). Conversely, the groove angle (θ1b, θ2b) of the wide inner groove pattern (L1b, L2b) is smaller than the groove angle (θ1a, θ2a) of the narrow outer groove pattern (L1a, L2a). .. (Specifically, a difference in angle of about 2 times is provided for a difference in width of 2 times.) Generally speaking, the left and right groove patterns (L1a, L1b or) of the plane part (L1c or L2c) are provided. Regarding L2a, L2b), assuming that the width, depth, alignment pitch, surface condition in the grooves, etc. of multiple grooves in each groove pattern are uniform, it is approximately 1 / N for an increase in groove pattern width N times. The groove angle reduction is set.

This is the total amount of liquid metal LM that is scraped into the groove of the narrow outer groove pattern (L1a or L2a) as the shaft 112 rotates, and the liquid metal LM that is scraped into the groove of the wide inner groove pattern (L1b or L2b). This is to make the total amount of the above substantially the same. Then, the total amount of the liquid metal LM scraped into the multiple grooves of the groove patterns (L1a, L1b or L2a, L2b) having different widths provided on the left and right of the plane portion (L1c or L2c) is the plane portion (L1c or L2c). It will be balanced on the left and right of. As a result, the dynamic pressure bearing operation in each of the left and right slide bearing portions 110a and 110b is stabilized.

FIG. 5 is a diagram illustrating a modified example of FIG. 4 (difference in angle of groove pattern). In FIG. 4, the groove angles of the groove patterns (L1a, L1b; L2a, L2b) having different widths provided on the left and right of the plane portion (L1c; L2c) are changed (for example, θ1a = 65 °, θ1b = 30 °; θ2a = 65 °, θ2b = 30 °). On the other hand, in FIG. 5, these groove angles are the same (for example, θ1a = 60 °, θ1b = 60 °; θ2a = 60 °, θ2b = 60 °). Then, the total amount of the liquid metal LM scraped into the multiple grooves of the groove patterns (L1a, L1b or L2a, L2b) having different widths provided on the left and right of the plane portion (L1c or L2c) is the plane portion (L1c or L2c). It becomes unbalanced on the left and right. However, when the imbalance of the total amount of liquid metal scraped is small enough to be practically acceptable (for example, when the liquid metal is not depleted anywhere in the slide bearing), even in the slide bearing structure of FIG. 5, the rotary anode is used. It is possible to design and manufacture the target 106 in which the left and right slide bearing portions 110a and 110b stably support the shaft.

FIG. 6 is a diagram illustrating an example of the relationship between the slide bearing structure of FIG. 3 and the rotary anode target 106 of FIG. 1 or 2 (No. 2: Example of the target 106 not facing the bearing 110b). In the structure of FIG. 6, the positions of the left and right slide bearing portions 110a and 110b are displaced by equal intervals (or the same ratio) farther from the position of the center of gravity G of the rotating anode target 106 as compared with the structure of FIG. 4 or 5. ing. Due to this equidistant (or equal ratio) positional deviation, the axial support stability with respect to the rotary anode target 106 is further improved while maintaining the axial support balance of the left and right slide bearing portions 110a and 110b with respect to the rotary anode target 106.

In FIG. 6, the rotating anode target 106 does not overlap with the inner groove patterns L1b and L2b. Therefore, the plane portion L1c and the plane portion L2c are less likely to receive the thermal stress of the target 106. In the structure of FIG. 4 or 5, the overlap portion is a heat flow path that allows heat from the rotary anode target 106 to escape to the shaft 112 side of the slide bearing 110. Since there is no such heat flow path, the cooling capacity for the target 106 is reduced in the structure of FIG. 6, but even so, the ultra-thin (corresponding to g1 in FIG. 3) liquid metal layers of the left and right plain bearing portions 110a and 110b are interposed. Another heat flow path is secured. Therefore, depending on the heat generation condition of the rotating anode target 106, it is possible to design and manufacture the slide bearing 110 having the necessary and sufficient cooling performance even with the structure of FIG.

FIG. 7 is a diagram illustrating a comparative example (difference in width of the groove pattern) of FIG. In the structure of FIG. 7, the widths of the outer groove pattern and the inner groove pattern are equal (L1a = L1b; L2a = L2b) in the left and right slide bearing portions 110a and 110b, respectively, and the groove angles of the outer groove pattern and the inner groove pattern are equal (L1a = L1b; L2a = L2b). θ1a = θ1b; θ2a = θ2b). The structure of FIG. 7 has an overlap portion similar to that of FIG. 4 or 5 between the rotary anode target 106 and the inner groove pattern L2b, and this overlap portion heats from the rotary anode target 106 of the plain bearing 110. It is a heat flow path that escapes to the shaft 112 side. Even with the plain bearing structure shown in FIG. 7, it is possible to design and manufacture the rotary anode target 106 so as to be stably pivotally supported by the left and right plain bearing portions 110a and 110b.

The plane portion L1c of FIG. 7 is equal to the plane portion L1c of FIGS. 4 and 5. Further, the plane portion L2c in FIG. 7 is equal to the plane portion L2c in FIGS. 4 and 5.
By the way, the distance D1a in FIG. 7 is shorter than the distance D1a in FIGS. 4 and 5. Similarly, the distance D2a in FIG. 7 is shorter than the distance D2a in FIGS. 4 and 5. From the above, the plain portion L1c and the plane portion L2c are less likely to receive the thermal stress of the target 106 in the slide bearing structure of FIGS. 4 and 5 than in the slide bearing structure of FIG. 7.

FIG. 8 is a partial cross-sectional view illustrating an example of the internal structure of the X-ray tube according to another embodiment.

The rotary anode X-ray tube 100 of this embodiment includes a vacuum vessel 102, a structure of a rotary anode target 106 housed in the vacuum vessel 102, and a bearing rotating portion of a sliding bearing that rotatably supports the structure. 113, a fixed shaft 118 coaxially connected to the shaft 112 of the sliding bearing, a cathode 104 that emits an electron beam toward the rotating anode target 106, and a stator provided outside the vacuum vessel 102 to generate a rotating magnetic field. It is provided with a coil 11. The motor rotor 115 that receives the magnetic field from the stator coil has a laminated structure of the outer cylinder 15a of the conductor and the inner cylinder 15b of the magnetic material (soft iron), and forms an eddy current type motor in combination with the coil 11.

An anode target layer with which an electron beam collides is formed on the umbrella-shaped outer surface of the rotating anode target 106. The rotating anode target 106 and the anode target layer are made of refractory metal, and for example, molybdenum, tungsten or alloys thereof are used.

The structure of the slide bearing 110 as shown in any of FIGS. 3 to 7 can be applied to the inside of the bearing rotating portion 113 of FIG.

Although embodiments of the present invention have been described, the above embodiments are presented as examples and are not intended to limit the scope of the invention. The above-mentioned novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The above embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.
For example, the width of the first inner groove pattern L1b is set to be larger than the width of the first outer groove pattern L1a (L1a <L1b), and the width of the second inner groove pattern L2b is the second outer groove pattern L2a. When the width is set larger than (L2a <L2b), the width of the first outer groove pattern L1a and the width of the second outer groove pattern L2a are equal (L1a = L2a), and the width of the first inner groove pattern L1b The width may be equal to the width of the second inner groove pattern L2b (L1b = L2b).

<Summary of embodiments>
In a rotary anode X-ray tube having a liquid metal slide bearing, the groove pattern (L1a, L1b; L2a, L2b) provided on the fixed shaft (112) side of the slide bearing is asymmetrically configured and is provided in the middle of the slide bearing. The plane portion (L1c; L2c) is configured to be displaced from the bearing center (G). This alleviates the decrease in load capacity due to the deformation of the sliding bearing rotating portion (113) caused by the thermal stress from the rotating anode target (106), and provides a highly cooled rotating anode X-ray tube with high G resistance. do.

In a rotating anode X-ray tube in which a rotating anode target (106) and a sliding bearing rotating portion (113) are integrally formed and the rotating anode target (106) is cooled via the sliding bearing rotating portion (113), the rotating anode target In order to support (106), a cylindrical surface forming two divided sliding bearing portions (110a, 110b) is configured on the shaft (112). Groove patterns (L1a, L1b; L2a, L2a, L1b; L2a, L1b; L1a, L1b; L2b) and a plane portion (L1c, L2c) for independently supporting the rotating anode target (106) are formed between the left and right groove patterns. The rotary anode target (106) is configured to be located between the two slide bearing portions (110a, 110b) configured in this way, and heat generated in the rotary anode target (106) is transferred to the slide bearing portion (110a, 110a, It has a high cooling structure that cools through 110b). Here, the width of the left and right groove patterns (L1a, L1b; L2a, L2b) formed in the slide bearing portions (110a, 110b) in the shaft axial length direction is outside when viewed from the position of the rotary anode target (106). Narrow and wide inside. As a result, the intermediate plane portion (L1c, L2c) is arranged outside the wide inner groove pattern. In such a configuration, even if the rotating anode target (106) expands at a high temperature, the middle of the sliding bearing rotating portion (113) swells, and the gap diameter in the rotating portion (113) expands with eccentricity, it is caused by this. Prevent a decrease in load capacity. Therefore, the plane portion (L1c, L2c) is arranged at a position that is not affected by the thermal deformation of the target (106), which is farther from the target position (G) than the normal configuration. This makes it possible to provide a highly cooled rotary anode X-ray tube having high G resistance.

The rotating anode X-ray tube using the slide bearing structure according to the embodiment of the present invention can be applied to various X-ray systems. For example, it can be applied to various systems such as an X-ray stereo radiography system, an X-ray stereo cine radiography system, and a stereo pulse fluoroscopy system.

According to the slide bearing structure according to the embodiment of the present invention, it is possible to provide a slide bearing that supports a rotating body that becomes hot while cooling and has G resistance. The rotating body that becomes hot is not necessarily limited to the target that generates X-rays, and can be applied to, for example, the cooling shaft support of a drill (or a rotary grindstone) that becomes hot due to frictional heat during machining. When the slide bearing structure according to the embodiment of the present invention is applied to a cooling shaft support such as a drill, the bearing structure does not have to be housed in a vacuum container.

<Points of the embodiment>
According to the slide bearing structure according to the embodiment, the plain parts (L1c, L2c) of the slide bearing parts (110a, 110b) can be separated from the rotating anode target (106) which becomes a high temperature, and the G resistance performance is deteriorated. Can be prevented.

Further, even in the groove groove pattern (L1b; LL2b) on the side close to the rotating anode target (106), it is possible to release the heat from the rotating anode target (106) via the liquid metal as a lubricant that easily conducts heat. Is. That is, both G-resistant performance and high cooling function can be achieved.

If the shape of the groove pattern (L1a, L1b or L2a, L2b) is asymmetrical, the amount of liquid metal drawn will change, so the liquid metal will move to the side with the smaller amount of scraping and the liquid metal will move into the bearing. There is a risk of uneven distribution. As a result, the liquid metal may be depleted in a part of the slide bearing portions (110a, 110b), and the function of the slide bearing may be impaired. To solve this problem, the groove scratching angle (θ1a, θ2a) of the groove pattern (L1a, L2a) on the side away from the anode target, which is narrow in the axial direction of the shaft, is widened on the side close to the anode target. We propose a method of making the groove pattern (L1b, L2b) larger than the groove scraping angle (θ1b, θ2b) and making the liquid metal scraping amount of the left and right groove patterns (L1b, L2b) the same. In the calculation, for example, when the axial width of the groove pattern is doubled, it is known that the scraping amount can be made the same by doubling the scraping angle or more. Can be dealt with.

<Additional notes corresponding to the initial claims>
[1] The slide bearing structure according to the embodiment has a structure in which a shaft (112) and a target (106) having a temperature higher than that of the shaft are rotatably supported by the shaft. In this plain bearing structure, the shaft (112) includes a plain bearing (110) having a plurality of groove patterns (L1a, L1b; L2a, L2b) in the axial length direction of the shaft.

One of the plurality of bearing portions (110a, 110b) constituting the slide bearing (110) (for example, 110a) includes an outer groove pattern (L1a) and an inner groove pattern (L1b) in the axial length direction of the shaft. A plain portion (L1c) is included between these groove patterns.

When viewed in the axial length direction of the shaft (112), the width of the inner groove pattern (L1b) is larger than the width of the outer groove pattern (L1a), and the position of the inner groove pattern (L1b) is the outer groove. It is closer to the target (106) than the position of the pattern (L1a). Then, the position of the plane portion (L1c) is configured to be at a position farther (for example, D1a away) than the position of the inner groove pattern (L1b) with respect to the target (106).

[2] The slide bearing structure according to another embodiment has a structure in which a shaft (112) and a target (106) having a higher temperature than the shaft are rotatably supported on the shaft. In this plain bearing structure, the shaft (112) includes a plain bearing (110) having a plurality of groove patterns (L1a, L1b; L2a, L2b) in the axial length direction of the shaft. The plain bearing (110) includes a first plain bearing portion (110a) and a second plain bearing portion (110b).

The first slide bearing portion (110a) includes a first outer groove pattern (L1a) and a first inner groove pattern (L1b) in the axial length direction of the shaft, and a first among these groove patterns. Includes the plain part (L1c) of. Further, the second slide bearing portion (110b) includes a second outer groove pattern (L2a) and a second inner groove pattern (L2b) in the axial length direction of the shaft, and is between these groove patterns. Includes a second plane portion (L2c).

When viewed in the axial length direction of the shaft (112), the width of the first inner groove pattern (L1b) is larger than the width of the first outer groove pattern (L1a), and the width of the second inner groove pattern (L1a) is larger than the width of the first outer groove pattern (L1a). The width of (L2b) is larger than the width of the second outer groove pattern (L2a). Further, when viewed in the axial length direction of the shaft (112), the position of the first inner groove pattern (L1b) is closer to the target (106) than the position of the first outer groove pattern (L1a). The position of the second inner groove pattern (L2b) is closer to the target (106) than the position of the second outer groove pattern (L2a).

The position of the first plane portion (L1c) is at a position (D1a) away from the position of the first inner groove pattern (L1b) with respect to the target (106), and the position of the second plane portion (L2c) is located. ) Is located at the position (D2a) farther from the position of the second inner groove pattern (L2b) with respect to the target (106). Then, when viewed in the axial length direction of the shaft (112), the center of gravity (106) of the target (106) is located between the first inner groove pattern (L1b) and the second inner groove pattern (L2b). G; It is configured so that FIGS. 4 to 7) come.

[3] In the slide bearing structure of [1], the outer groove pattern (L1a) has a first angle in the first rotation direction (counterclockwise) with respect to an axis perpendicular to the axial length direction of the shaft (112). It is composed of a plurality of grooves having (θ1a), and the inner groove pattern (L1b) has a second rotation direction opposite to the first rotation direction with respect to an axis perpendicular to the axial length direction of the shaft (112). It is composed of a plurality of grooves having a second angle (θ1b) (clockwise).

When viewed in the axial length direction of the shaft (112) (the shaft diameter φ of the plane portion is, for example, 40 mm), the width (for example, 8 mm to 10 mm) of the inner groove pattern (L1b) is the outer groove pattern (L1a). Is set to be larger than the width of (for example, 5 mm to 8 mm) (L1a <L1b), and the first angle (θ1a; for example, 60 ° to 65 °) is equal to or larger than the second angle (θ1b; for example, 30 ° to 60 °). Is set to (θ1b ≤ θ1a).

[4] In the slide bearing structure of [2], the first outer groove pattern (L1a) is the first in the rotation direction (counterclockwise) with respect to the axis perpendicular to the axial length direction of the shaft (112). It is composed of a plurality of grooves having an angle of 1 (θ1a), and the first inner groove pattern (L1b) is opposite to the first rotation direction with respect to the axis perpendicular to the axial length direction of the shaft (112). It is composed of a plurality of grooves having a second angle (θ1b) in the second rotation direction (clockwise) of the above.

Further, the second inner groove pattern (L2b) has a plurality of angles (θ2b) in the first rotation direction (counterclockwise) with respect to the axis perpendicular to the axial length direction of the shaft (112). The second outer groove pattern (L2a) is a fourth angle (θ2a) in the second rotation direction (clockwise) with respect to an axis perpendicular to the axial length direction of the shaft (112). Consists of multiple grooves with.

The width (for example, 8 mm to 10 mm) of the first inner groove pattern (L1b) when viewed in the axial length direction of the shaft (112) (the shaft diameter φ of the first and second plane portions is, for example, 40 mm). Is set larger than the width of the first outer groove pattern (L1a) (for example, 5 mm to 8 mm) (L1a <L1b), and the width of the second inner groove pattern (L2b) is set to be larger than the width (for example, 12 mm to 16 mm). The width of the outer groove pattern (L2a) of 2 is set to be larger than the width (for example, 8 mm to 12 mm) (L2a <L2b), and the first angle (θ1a; for example, 60 ° to 65 °) is the second angle (θ1b; For example, it is set to be 30 ° to 60 ° or more (θ1b ≦ θ1a), and the fourth angle (θ2a; for example, 60 ° to 65 °) is set to the third angle (θ2b; for example, 30 ° to 60 °) or more. It is set (θ1b ≤ θ1a).

[5] In the slide bearing structures of [1] to [4],
A bearing rotating portion formed integrally with the target by inserting the shaft into the inside,
Further comprising a liquid metal (LM) present in the gap between the shaft and the bearing rotating portion.
On the surface of the shaft (112), a gap (g2: for example, 100 μm) between the shaft and the bearing rotating portion in an area including the center of gravity (G) of the target (106) (for example, an area having a width La1) is provided. , Larger than the gap (g1: eg 10 μm) between the shaft and the bearing rotating portion in the area of one (eg 110a) of the plurality of bearing portions (110a, 110b) constituting the slide bearing (110). ..

[6] The slide bearing structures of [1] to [5] can be applied to the rotating shaft support of the target in an X-ray tube that generates X-rays by colliding an electron beam with the rotating target (106).

[7] The rotating anode X-ray tube (100) according to the embodiment includes a rotating anode target (106) and a cathode (104) that causes an electron beam to collide with the anode target (106). In this X-ray tube (100), the anode target (106) is rotatably supported between two slide bearing portions (110a, 110b) formed on the shaft (112) of the slide bearing.

Each of the two plain bearing portions (110a, 110b) has an outer groove pattern (L1a, L2a), an inner groove pattern (L1b, L2b), and a plain portion (L1c, L2c) between these groove patterns.

The plain portion (L1c, L2c) is configured to separate from the anode target (106) (D1a, D2a or D1b, D2b) due to the presence of the inner groove pattern (L1b, L2b), and from the anode target (106). Is configured to dissipate heat to the shaft (112) side via at least one of the two slide bearing portions (110a, 110b).

[8] In the rotary anode X-ray tube (100) of [7], the width of the inner groove pattern (L1b, L2b) is the width of the outer groove pattern (L1a, L2a) when viewed in the axial length direction of the shaft (112). It is made larger than the width, and the groove angle (60 ° to 65 °) of the outer groove pattern (L1a, L2a) is set to be equal to or larger than the groove angle (30 ° to 60 °) of the inner groove pattern (L1b, L2b).

100 ... X-ray tube; 102 ... Vacuum container; 104 ... Electron gun (cathode); 106 ... Rotating anode target; 110 ... Slide bearings; 110a, 110b ... Left and right slide bearings; 111 ... Motor stator; 112 ... Slide bearings Shaft; 113 ... Bearing rotating part; 115 ... Motor rotor.

Claims (5)

In a plain bearing structure that rotatably supports a shaft and a target that is hotter than this shaft on this shaft.
A bearing rotating portion formed integrally with the target by inserting the shaft into the inside,
Further comprising a liquid metal present in the gap between the shaft and the bearing rotating portion.
The shaft comprises a plain bearing having a plurality of groove patterns in the axial length direction of the shaft.
One of the plurality of bearing portions constituting the slide bearing includes an outer groove pattern and an inner groove pattern in the axial length direction of the shaft, and includes a plane portion between these groove patterns.
When viewed in the axial length direction of the shaft, the width of the inner groove pattern is larger than the width of the outer groove pattern, and the position of the inner groove pattern is closer to the target than the position of the outer groove pattern. ,
The position of the plane portion is configured to be farther from the position of the inner groove pattern when viewed from the target.
The outer groove pattern is composed of a plurality of grooves on the surface of the shaft, which form a first angle with the axial direction of the shaft.
The inner groove pattern is composed of a plurality of grooves on the surface of the shaft, which form a second angle with the axial direction of the shaft.
The direction of each of the grooves is the direction in which the liquid metal is scraped into the plane portion as the shaft rotates.
The first angle is set to be equal to or higher than the second angle.
Plain bearing structure. In a plain bearing structure that rotatably supports a shaft and a target that is hotter than this shaft on this shaft.
A bearing rotating portion formed integrally with the target by inserting the shaft into the inside,
Further comprising a liquid metal present in the gap between the shaft and the bearing rotating portion.
The shaft comprises a plain bearing having a plurality of groove patterns in the axial length direction of the shaft.
The plain bearing includes a first plain bearing portion and a second plain bearing portion.
The first slide bearing portion includes a first outer groove pattern and a first inner groove pattern in the axial length direction of the shaft, and includes a first plane portion between these groove patterns.
The second plain bearing portion includes a second outer groove pattern and a second inner groove pattern in the axial length direction of the shaft, and includes a second plane portion between these groove patterns.
When viewed in the axial length direction of the shaft, the width of the first inner groove pattern is larger than the width of the first outer groove pattern, and the width of the second inner groove pattern is the width of the second outer groove. Larger than the width of the pattern,
When viewed in the axial length direction of the shaft, the position of the first inner groove pattern is closer to the target than the position of the first outer groove pattern, and the position of the second inner groove pattern is located. Is closer to the target than the position of the second outer groove pattern.
The position of the first plane portion is located at a position farther from the position of the first inner groove pattern with respect to the target.
The position of the second plane portion is located at a position farther from the position of the second inner groove pattern with respect to the target.
When viewed in the axial length direction of the shaft, the center of gravity of the target is configured to be between the first inner groove pattern and the second inner groove pattern.
The first outer groove pattern is composed of a plurality of grooves on the surface of the shaft at a first angle with the axial direction of the shaft.
The first inner groove pattern is composed of a plurality of grooves on the surface of the shaft at a second angle with the axial direction of the shaft.
The second inner groove pattern is composed of a plurality of grooves on the surface of the shaft at a third angle with the axial direction of the shaft.
The second outer groove pattern is composed of a plurality of grooves on the surface of the shaft at a fourth angle with the axial direction of the shaft.
The direction of each of the grooves in the first slide bearing portion is the direction in which the liquid metal is scraped into the first plane portion as the shaft rotates.
The direction of each of the grooves in the second slide bearing portion is the direction in which the liquid metal is scraped into the second plane portion as the shaft rotates.
The first angle is set to be equal to or higher than the second angle.
The fourth angle is set to be equal to or higher than the third angle.
Plain bearing structure. In the slide bearing structure according to claim 1 or 2.
In the surface of the shaft, the gap between the shaft and the bearing rotating portion in the area including the center of gravity of the target is the shaft and the bearing rotation in one area of the plurality of bearing portions constituting the slide bearing. It is larger than the gap between the bearings. An X-ray tube using the slide bearing structure according to any one of claims 1 to 3 and configured to generate X-rays by colliding an electron beam with the rotating target. In an X-ray tube comprising a rotating anode target, a cathode that causes an electron beam to collide with the anode target, a bearing rotating portion, and a liquid metal.
The anode target is rotatably supported between two slide bearing portions formed on the shaft of the slide bearing.
Each of the two plain bearing portions has a plain portion between the outer groove pattern, the inner groove pattern, and these groove patterns.
In each of the plain bearing portions, the position of the inner groove pattern is closer to the anode target than the position of the outer groove pattern when viewed in the axial length direction of the shaft.
In each of the plain bearing portions, the position of the plane portion is located at a position farther from the position of the inner groove pattern with respect to the anode target.
The heat from the anode target is configured to be dissipated to the shaft side via the two slide bearing portions.
The bearing rotating portion is formed integrally with the anode target by inserting the shaft inside.
The liquid metal exists in the gap between the shaft and the bearing rotating portion, and is present.
In each of the plain bearing portions, the width of the inner groove pattern is larger than the width of the outer groove pattern when viewed in the axial length direction of the shaft.
In the slide bearing portion of one of the two slide bearing portions,
The outer groove pattern is composed of a plurality of grooves on the surface of the shaft, which form a first angle with the axial direction of the shaft.
The inner groove pattern is composed of a plurality of grooves on the surface of the shaft, which form a second angle with the axial direction of the shaft.
In the other slide bearing portion of the two slide bearing portions,
The inner groove pattern is composed of a plurality of grooves on the surface of the shaft at a third angle with the axial direction of the shaft.
The outer groove pattern is composed of a plurality of grooves on the surface of the shaft at a fourth angle with the axial direction of the shaft.
The direction of each of the grooves in the one slide bearing portion is the direction in which the liquid metal is scraped into the plane portion of the one slide bearing portion as the shaft rotates.
The direction of each of the grooves in the other slide bearing portion is the direction in which the liquid metal is scraped into the plane portion of the other slide bearing portion as the shaft rotates.
The first angle is set to be equal to or higher than the second angle.
The fourth angle is set to be equal to or higher than the third angle.
Rotating anode X-ray tube.

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