Hydrostatic bearing spindle

Abstract

To provide a hydrostatic bearing spindle with improved load-bearing characteristics. [Solution] The hydrostatic bearing spindle 1 comprises a rotating shaft 10, a radial bearing sleeve 21, a thrust bearing sleeve 50, and a magnet 55. The rotating shaft 10 includes a shaft portion 11 extending in the thrust direction T and a thrust plate 12 extending from the shaft portion 11 in the radial direction R. The thrust bearing sleeve 50 and the magnet 55 are positioned in the thrust direction T on the side opposite to the radial bearing sleeve 21 relative to the thrust plate 12.

Description

Technical Field

[0001] The present disclosure relates to a hydrostatic bearing spindle.

Background Art

[0002] Japanese Patent No. 6935766 (Patent Document 1) and Japanese Patent No. 7035594 (Patent Document 2) disclose spindle devices.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the posture of the spindle device changes and the angle of the rotating shaft that rotates at high speed changes, a gyro moment is generated on the rotating shaft. Further, if there is an imbalance in the weight of the rotating shaft in the circumferential direction of the rotating shaft, the rotating shaft may vibrate when the rotating shaft is rotated. Thus, loads caused by the gyro moment and the vibration of the rotating shaft act on the rotating shaft. The present disclosure has been made in view of the above problems, and an object thereof is to provide a hydrostatic bearing spindle having improved load resistance characteristics.

Means for Solving the Problems

[0005] The hydrostatic bearing spindle of this disclosure comprises a rotating shaft, a radial bearing sleeve, a thrust bearing sleeve, and a magnet. The rotating shaft includes a shaft portion extending in the thrust direction, a thrust plate extending radially from the shaft portion intersecting the thrust direction, and turbine blades provided on the thrust plate. The radial bearing sleeve is positioned opposite the shaft portion in the radial direction. The thrust bearing sleeve is positioned opposite the thrust plate in the thrust direction. The magnet attracts the rotating shaft in the thrust direction. A radial bearing supporting the shaft portion in the radial direction is formed between the shaft portion and the radial bearing sleeve. A thrust bearing supporting the rotating shaft in the thrust direction is formed between the thrust plate and the thrust bearing sleeve. The thrust bearing sleeve and the magnet are positioned in the thrust direction on the side opposite to the radial bearing sleeve relative to the thrust plate. The thrust distance from the thrust bearing to the center of the radial bearing in the thrust direction is greater than the diameter of the center of the thrust bearing in the radial direction. [Effects of the Invention]

[0006] The hydrostatic bearing spindle of this disclosure has improved load-bearing characteristics. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view of the hydrostatic bearing spindle of the embodiment. [Figure 2] This is a rear view of the rotating shaft included in the hydrostatic bearing spindle of the embodiment. [Figure 3] This is a schematic cross-sectional view of a hydrostatic bearing spindle in an embodiment that includes a bell cup. [Figure 4] This is a schematic cross-sectional view of a hydrostatic bearing spindle in an embodiment mounted on a spindle holder. [Figure 5] This is a schematic cross-sectional view of a hydrostatic bearing spindle of a first modified embodiment. [Figure 6] This is a schematic, partially enlarged cross-sectional view of a hydrostatic bearing spindle in the first example of a second modified embodiment. [Figure 7]This is a schematic partially enlarged cross-sectional view of a hydrostatic bearing spindle in a second example of a second modified embodiment. [Figure 8] This is a schematic, partially enlarged cross-sectional view of a hydrostatic bearing spindle in a third example of a second modified embodiment. [Figure 9] This is a schematic, partially enlarged cross-sectional view of a hydrostatic bearing spindle of a third modified embodiment. [Figure 10] This is a schematic, partially enlarged cross-sectional view of the radial bearing of a hydrostatic bearing spindle in the first example of a fourth modified embodiment. [Figure 11] This is a schematic, partially enlarged cross-sectional view of the thrust bearing of a hydrostatic bearing spindle in the first example of a fourth modified embodiment. [Figure 12] This is a schematic partially enlarged cross-sectional view of the radial bearing of a hydrostatic bearing spindle in a second example of a fourth modified embodiment. [Figure 13] This is a schematic, partially enlarged cross-sectional view of the thrust bearing of a hydrostatic bearing spindle in a second example of a fourth modified embodiment. [Figure 14] This is a schematic, partially enlarged cross-sectional view of the radial bearing of a hydrostatic bearing spindle in the third example of a fourth modified embodiment. [Figure 15] This is a schematic, partially enlarged cross-sectional view of the thrust bearing of a hydrostatic bearing spindle in the third example of a fourth modified embodiment. [Figure 16] This is a schematic partially enlarged cross-sectional view of the radial bearing of a hydrostatic bearing spindle in the fourth example of a fourth modified embodiment. [Figure 17] This is a schematic, partially enlarged cross-sectional view of the thrust bearing of a hydrostatic bearing spindle in the fourth example of a fourth modification of the embodiment. [Figure 18] This is a schematic partially enlarged cross-sectional view of the radial bearing of a hydrostatic bearing spindle in a fifth example of a fourth modified embodiment. [Figure 19] This is a schematic, partially enlarged cross-sectional view of the thrust bearing of a hydrostatic bearing spindle in a fifth example of a fourth modified embodiment. [Modes for carrying out the invention]

[0008] The details of the embodiments of the present disclosure will be described based on the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated. At least some of the configurations of the embodiments described below may be arbitrarily combined.

[0009] Referring to FIGS. 1 to 4, the hydrostatic bearing spindle 1 of the embodiment will be described. The hydrostatic bearing spindle 1 is used, for example, in an electrostatic coating machine. The hydrostatic bearing spindle 1 includes a rotating shaft 10, a housing assembly 20, a cover 27, a plurality of O-rings 41, 42, 43, 44, a thrust bearing sleeve 50, a magnet 55, and a case 57. The hydrostatic bearing spindle 1 may further include a bell cup 19 (see FIGS. 3 and 4).

[0010] Referring to FIGS. 1, 3, and 4, the rotating shaft 10 is supported by a radial bearing 24 and a thrust bearing 53 and rotates around the axis O. The rotating shaft 10 includes a shaft portion 11, a thrust plate 12, and a plurality of turbine blades 15.

[0011] The shaft portion 11 extends in the thrust direction T. That is, the longitudinal direction of the shaft portion 11 is the thrust direction T. The shaft portion 11 includes a first end portion 11a, a second end portion 11b opposite to the first end portion 11a, and a central portion between the second end portion 11b and the first end portion 11a. The first end portion 11a and the second end portion 11b are both ends of the shaft portion 11 in the thrust direction T. Hereinafter, the side of the first end portion 11a in the thrust direction T is referred to as the rear side, and the side of the second end portion 11b is referred to as the front side. A first through hole 16 extending in the thrust direction T may be provided in the shaft portion 11. When the hydrostatic bearing spindle 1 is used in an electrostatic coating machine, a bell cup attachment portion 18 may be formed at the second end portion 11b.

[0012] The thrust plate 12 extends from the outer circumferential surface of the shaft portion 11 in a radial direction R intersecting the thrust direction T. The thrust plate 12 is provided, for example, at the first end 11a of the shaft portion 11. The thrust plate 12 includes a thick-walled portion 13 and a thin-walled portion 14. The thick-walled portion 13 is connected to the first end 11a of the shaft portion 11. The thickness of the thin-walled portion 14 in the thrust direction T is smaller than the thickness of the thick-walled portion 13 in the thrust direction T. The thin-walled portion 14 is located outside the thick-walled portion 13 in the radial direction R and surrounds the thick-walled portion 13. In this specification, the side farther from the axis O in the radial direction R is referred to as the outside, and the side closer to the axis O in the radial direction R is referred to as the inside. The thickness of the portion of the thin-walled portion 14 distal to the thick-walled portion 13 is, for example, constant. The thickness of the portion of the thin-walled portion 14 proximal to the thick-walled portion 13 gradually increases as it approaches the thick-walled portion 13. The front surface of the thin-walled portion 14 that is close to the thick-walled portion 13 is, for example, a curved surface. The rear surface of the thick-walled portion 13 and the rear surface of the thin-walled portion 14 are, for example, flush with each other.

[0013] Referring to Figure 2, a detection area 17 is formed on the rear surface of the thrust plate 12 (specifically, the rear surface of the thin-walled portion 14). The detection area 17 includes a plurality of regions that are divided in the rotational direction of the rotation axis 10. The plurality of regions include, for example, a first region 17a and a second region 17b. The reflectance of the first region 17a is different from that of the second region 17b. For example, the reflectance of the first region 17a is higher than that of the second region 17b.

[0014] Referring to Figures 1, 3, and 4, the plurality of turbine blades 15 are provided on the front surface of the thrust plate 12. Specifically, the plurality of turbine blades 15 extend from the front surface of the thin-walled portion 14 of the thrust plate 12 to the front side in the thrust direction T. The plurality of turbine blades 15 are arranged along the outer circumference of the thrust plate 12. The plurality of turbine blades 15 are located within the space 35 formed between the thin-walled portion 14 and the rear surface of the radial bearing sleeve 21. The rotating shaft 10 can rotate as the plurality of turbine blades 15 receive turbine gas ejected from the turbine nozzle 62.

[0015] Referring to Figures 3 and 4, when the hydrostatic bearing spindle 1 is used in an electrostatic painting machine, the bell cup 19 is attached to the bell cup mounting portion 18. The bell cup 19 is fitted or screwed into the bell cup mounting portion 18, for example. Paint supplied from the paint spray nozzle 78 (see Figure 4) is supplied to the bell cup 19. Centrifugal force acts on the paint due to the bell cup 19 rotating at high speed together with the rotating shaft 10, causing the paint to be atomized into fine particles.

[0016] Referring to Figures 1, 3, and 4, the housing assembly 20 accommodates a portion of the shaft portion 11. The housing assembly 20 includes a radial bearing sleeve 21 and a housing 25.

[0017] The radial bearing sleeve 21 is positioned opposite the shaft portion 11 (more specifically, the central portion of the shaft portion 11) in the radial direction R, and surrounds a part of the shaft portion 11. A radial bearing clearance 23 is formed between the shaft portion 11 and the radial bearing sleeve 21. In the thrust direction T, the radial bearing sleeve 21 is positioned in front of the thrust plate 12. The rear surface of the radial bearing sleeve 21 faces the front surface of the thrust plate 12 in the thrust direction T. A first nozzle 22 is provided on the radial bearing sleeve 21 through which the first bearing gas flows out in the radial direction R toward the shaft portion 11.

[0018] The housing 25 is positioned outside the radial bearing sleeve 21 in the radial direction R. The housing 25 accommodates the radial bearing sleeve 21. The housing 25 is fixed to the radial bearing sleeve 21.

[0019] The cover 27 is positioned radially outward from the housing 25 in direction R. The cover 27 covers the housing 25 and houses the housing 25.

[0020] The housing 25, radial bearing sleeve 21, and cover 27 are formed to supply a first bearing gas to the radial bearing clearance 23. Specifically, a first bearing gas supply passage 30 is provided in the housing 25, radial bearing sleeve 21, and cover 27. One end of the first bearing gas supply passage 30 is connected to a first bearing gas inlet 31 provided on the outer circumferential surface of the cover 27. The other end of the first bearing gas supply passage 30 is connected to a first nozzle 22 of the radial bearing sleeve 21. The diameter of the first nozzle 22 may be smaller than the diameter of the first bearing gas inlet 31, and the first nozzle 22 may be a throttling. As the first bearing gas is supplied to the radial bearing clearance 23 through the first bearing gas inlet 31 and the first bearing gas supply passage 30, a radial bearing 24 supporting the shaft portion 11 in the radial direction R is formed between the shaft portion 11 and the radial bearing sleeve 21.

[0021] The housing 25, radial bearing sleeve 21, and cover 27 are formed to allow exhaust of turbine gas supplied to multiple turbine blades 15. Specifically, a turbine gas exhaust passage 33 is provided in the housing 25, radial bearing sleeve 21, and cover 27. One end of the turbine gas exhaust passage is connected to a turbine gas exhaust port 34 provided on the outer circumferential surface of the cover 27. The turbine gas exhaust port 34 is located behind the first bearing gas inlet 31 in the thrust direction T. The other end of the turbine gas exhaust passage 33 communicates with a space 35 formed between the thin-walled portion 14 of the thrust plate 12 and the rear surface of the radial bearing sleeve 21.

[0022] Referring to Figures 1, 3, and 4, the multiple O-rings 41, 42, 43, and 44 are positioned between the housing 25 and the cover 27, and elastically support the housing 25 relative to the cover 27. The multiple O-rings 41, 42, 43, and 44 are formed of, for example, a perfluoroelastomer, which is a fluorine-based rubber. Therefore, when the hydrostatic bearing spindle 1 is used in an electrostatic painting machine, the multiple O-rings 41, 42, 43, and 44 have high resistance to paint solvents.

[0023] O-ring 41 is positioned outside the thrust plate 12 in the radial direction R. In the thrust direction T, O-ring 41 is positioned furthest back among the multiple O-rings 41, 42, 43, and 44. In the thrust direction T, O-ring 41 is positioned between the thrust bearing 53 and the center C1 of the radial bearing 24 in the thrust direction T. O-ring 42 is positioned outside the central part of the shaft portion 11 in the radial direction R. In the thrust direction T, O-ring 42 is positioned in front of O-ring 41. In the thrust direction T, O-ring 42 is positioned between the thrust plate 12 and the center C1 of the radial bearing 24 in the thrust direction T.

[0024] O-ring 43 is positioned outside the radial direction R relative to the center of the shaft portion 11. In the thrust direction T, O-ring 43 is positioned in front of O-ring 42. In the thrust direction T, at least one of the multiple O-rings 41, 42, 43, 44 (for example, O-ring 43) is positioned between the center C1 of the radial bearing 24 and the center of gravity G1 of the rotating shaft 10 (see Figures 1 and 3). In the thrust direction T, at least one of the multiple O-rings 41, 42, 43, 44 (for example, O-ring 43) is positioned between the center C1 of the radial bearing 24 and the overall center of gravity G2 of the rotating shaft 10 and the bell cup 19 (see Figure 3).

[0025] O-ring 44 is positioned outside the central part of the shaft portion 11 in the radial direction R. In the thrust direction T, O-ring 44 is positioned in front of O-ring 43. In the thrust direction T, O-ring 44 is positioned furthest forward of the multiple O-rings 41, 42, 43, 44. In the thrust direction T, at least one of the multiple O-rings 41, 42, 43, 44 (for example, O-ring 44) is positioned between the center of gravity G1 of the rotating shaft 10 and the center of gravity G3 of the bell cup 19 (see Figure 3). In the thrust direction T, at least one of the multiple O-rings 41, 42, 43, 44 (for example, O-ring 44) is positioned between the overall center of gravity G2 of the rotating shaft 10 and the bell cup 19 (see Figure 3) and the center of gravity G3 of the bell cup 19 (see Figure 3).

[0026] Referring to Figures 1, 3, and 4, the thrust bearing sleeve 50 is positioned opposite the thrust plate 12 in the thrust direction T. A thrust bearing clearance 52 is formed between the thrust plate 12 and the thrust bearing sleeve 50. In the thrust direction T, the thrust bearing sleeve 50 is positioned on the side opposite to the radial bearing sleeve 21 relative to the thrust plate 12. Specifically, in the thrust direction T, the thrust bearing sleeve 50 is positioned behind the thrust plate 12. The front surface of the thrust bearing sleeve 50 faces the rear surface of the thrust plate 12 (specifically, the rear surface of the thickened portion 13) in the thrust direction T. A second nozzle 51 is provided on the thrust bearing sleeve 50 through which the second bearing gas flows out toward the thrust plate 12 in the thrust direction T. The second nozzle 51 may be positioned on the center of the front surface of the thrust bearing sleeve 50 in the radial direction R. The center of the front surface of the thrust bearing sleeve 50 in the radial direction R is midway between the inner and outer edges of the front surface of the thrust bearing sleeve 50. The second nozzle 51 may be positioned on the center C2 of the thrust bearing 53 in the radial direction R.

[0027] Referring to Figures 1, 3, and 4, the magnet 55 applies a magnetic force to the thrust plate 12, attracting the rotating shaft 10 in the thrust direction T. The magnet 55 is, for example, a permanent magnet. The magnet 55 is positioned in the thrust direction T on the side opposite to the radial bearing sleeve 21 relative to the thrust plate 12. Specifically, in the thrust direction T, the magnet 55 is positioned behind the thrust plate 12. The magnet 55 is positioned inward in the radial direction R relative to the thrust bearing sleeve 50. The magnet 55 faces the first end 11a of the shaft portion 11. The magnet 55 has a ring shape. The inner diameter of the magnet 55 may be approximately equal to the diameter of the first through hole 16. The magnet 55 may be coaxial with the first through hole 16. The front surface of the magnet 55 may be flush with the front surface of the thrust bearing sleeve 50, or it may be set back by a magnet gap g from the front surface of the thrust bearing sleeve 50.

[0028] Referring to Figures 1, 3, and 4, the case 57 houses the thrust bearing sleeve 50 and the magnet 55. For example, the front surface of the case 57 is provided with a first opening and a second opening. The thrust bearing sleeve 50 is inserted into the first opening. The magnet 55 is inserted into the second opening. The thrust bearing sleeve 50 and the magnet 55 are fixed to the case 57.

[0029] Referring to Figures 1, 3, and 4, a second through-hole 58 extending in the thrust direction T may be provided in the case 57. The second through-hole 58 communicates with the first through-hole 16. The second through-hole 58 may be coaxial with the first through-hole 16. The second through-hole 58 is located radially R inward from the magnet 55. The diameter of the second through-hole 58 is smaller than the inner diameter of the magnet 55. The second through-hole 58 is located radially R inward from the thrust bearing sleeve 50.

[0030] A third through-hole 59 extending in the thrust direction T may be provided in the case 57. The third through-hole 59 is located radially outward R from the magnet 55 and the thrust bearing sleeve 50. In the thrust direction T, the third through-hole 59 faces the detected part 17.

[0031] The case 57 is formed to supply turbine gas to a plurality of turbine blades 15. Specifically, the case 57 is provided with a turbine gas supply passage 60. One end of the turbine gas supply passage 60 is connected to a turbine gas inlet 61 located on the rear surface of the case 57. The turbine gas inlet 61 is located outside the second through-hole 58, the magnet 55, and the thrust bearing sleeve 50 in the radial direction R. The other end of the turbine gas supply passage 60 is connected to a turbine nozzle 62. The turbine nozzle 62 is configured to eject turbine gas toward the plurality of turbine blades 15 toward the radial direction R. The rotating shaft 10 rotates as the turbine gas is supplied to the plurality of turbine blades 15 through the turbine gas inlet 61 and the turbine gas supply passage 60.

[0032] Multiple turbine gas supply passages 60 and turbine nozzles 62 may be formed at intervals from each other in the rotational direction of the rotating shaft 10. In other words, the turbine gas supply passages 60 and turbine nozzles 62 may be arranged to simultaneously supply turbine gas in the same rotational direction to multiple turbine blades 15 that are spaced at arbitrary intervals in the rotational direction of the rotating shaft 10.

[0033] The case 57 and the thrust bearing sleeve 50 are formed to supply a second bearing gas to the thrust bearing clearance 52. Specifically, a second bearing gas supply passage 65 is provided in the case 57 and the thrust bearing sleeve 50. One end of the second bearing gas supply passage 65 is connected to a second bearing gas inlet 66 provided on the rear surface of the case 57. The second bearing gas inlet 66 is located outside the second through hole 58, the magnet 55, and the thrust bearing sleeve 50 in the radial direction R. The second bearing gas inlet 66 is located inside the turbine gas inlet 61 in the radial direction R. The other end of the second bearing gas supply passage 65 is connected to a second nozzle 51 of the thrust bearing sleeve 50. The diameter of the second nozzle 51 may be smaller than the diameter of the second bearing gas inlet 66, and the second nozzle 51 may be a throttle.

[0034] The supply of second bearing gas to the thrust bearing gap 52 through the second bearing gas inlet 66 and the second bearing gas supply passage 65 generates a force that presses the thrust plate 12 forward in the thrust direction T. The magnet 55 generates a force that attracts the thrust plate 12 backward in the thrust direction T. Due to the pressing force and the attracting force, a thrust bearing 53 is formed between the thrust plate 12 and the thrust bearing sleeve 50 to support the rotating shaft 10 in the thrust direction T. The thrust bearing 53 surrounds the first through hole 16. Therefore, the thrust bearing 53 prevents turbine gas from flowing into the first through hole 16 through the thrust bearing gap 52.

[0035] Referring to Figures 1 and 3, the distance L in the thrust direction T from the thrust bearing 53 to the center C1 of the radial bearing 24 in the thrust direction T is greater than the diameter D of the center C2 of the thrust bearing 53 in the radial direction R.

[0036] Referring to Figure 4, the spindle holder 70 houses the hydrostatic bearing spindle 1. Specifically, the spindle holder 70 is provided with a housing section 71. The hydrostatic bearing spindle 1 is housed in the housing section 71. The spindle holder 70 is provided with a bearing gas supply passage 72, a turbine gas supply passage 73, and a turbine gas exhaust passage 74. When the hydrostatic bearing spindle 1 is housed in the housing section 71, the bearing gas supply passage 72 is connected to the first bearing gas inlet 31 and the second bearing gas inlet 66, the turbine gas supply passage 73 is connected to the turbine gas inlet 61, and the turbine gas exhaust passage 74 is connected to the turbine gas exhaust port 34. The bearing gas supply passage 72 communicates with the first bearing gas supply passage 30 and the second bearing gas supply passage 65. The turbine gas supply passage 73 communicates with the turbine gas supply passage 60. The turbine gas exhaust passage 74 is connected to the turbine gas exhaust passage 33.

[0037] Referring to Figure 4, a paint supply passage 75 may be provided in the spindle holder 70. When the hydrostatic bearing spindle 1 is housed in the housing 71, the paint supply passage 75 is connected to the paint spray nozzle 78. Paint is supplied to the paint spray nozzle 78 through the paint supply passage 75. The paint spray nozzle 78 sprays the paint supplied from the paint supply passage 75.

[0038] Referring to Figure 4, the rotation sensor 76 can measure the rotational speed of the rotation shaft 10. The rotation sensor 76 is mounted on the spindle holder 70 via a sensor holder 77. When the hydrostatic bearing spindle 1 is housed in the housing 71, a portion of the rotation sensor 76 is inserted into the third through hole 59. The end of the rotation sensor 76 faces the detected portion 17 of the rotation shaft 10. The rotation sensor 76 is, for example, an optical rotation sensor 76. The rotation sensor 76 includes a light source (not shown) that can emit light to the detected portion 17 and a photodetector (not shown) that can detect reflected light from the detected portion 17. The light source is, for example, a semiconductor laser. The photodetector is, for example, a photodiode. When the rotation shaft 10 completes one rotation, the photodetector receives, for example, bright reflected light from a first region 17a (see Figure 2) of the detected portion 17 and dark reflected light from a second region 17b (see Figure 2) of the detected portion 17. Therefore, the rotation speed of the rotating shaft 10 can be measured by measuring the number of changes in the intensity of the reflected light from the detection unit 17.

[0039] The operation of the hydrostatic bearing spindle 1 in this embodiment will be described. The bearing gas supplied from a bearing gas supply source (not shown), such as an air compressor, flows into the bearing gas supply passage 72. In the bearing gas supply passage 72, the bearing gas is divided into a first bearing gas and a second bearing gas.

[0040] The first bearing gas is supplied to the radial bearing gap 23 through the first bearing gas inlet 31, the first bearing gas supply passage 30, and the first nozzle 22. In this way, the radial bearing 24 is formed between the shaft portion 11 and the radial bearing sleeve 21.

[0041] The second bearing gas is supplied to the thrust bearing gap 52 through the second bearing gas inlet 66, the second bearing gas supply passage 65, and the second nozzle 51. A force is generated that presses the thrust plate 12 forward in the thrust direction T. The magnet 55 generates a force that attracts the thrust plate 12 backward in the thrust direction T. Due to the pressing force and the attracting force, a thrust bearing 53 is formed between the thrust plate 12 and the thrust bearing sleeve 50.

[0042] Turbine gas supplied from a turbine gas supply source (not shown), such as an air compressor, is supplied to the turbine nozzle 62 through the turbine gas supply passage 73, the turbine gas inlet 61, and the turbine gas supply passage 60. The turbine gas is ejected from the turbine nozzle 62 inward in the radial direction R toward the multiple turbine blades 15. The multiple turbine blades 15 receive the turbine gas. Rotational torque is applied to the thrust plate 12. The rotating shaft 10 rotates around the axis O. The rotational speed of the rotating shaft 10 can be, for example, tens of thousands of rpm or more. Therefore, the hydrostatic bearing spindle 1 can be used in an electrostatic painting machine. The turbine gas is redirected by the curved surface on the front of the thrust plate 12 and flows into the turbine gas exhaust passage 33. The turbine gas is discharged to the outside of the hydrostatic bearing spindle 1 through the turbine gas exhaust passage 33, the turbine gas exhaust port 34, and the turbine gas exhaust passage 74.

[0043] (modified version) Referring to Figure 5, in the first modified embodiment, the magnet 55 is positioned outside the thrust bearing sleeve 50 in the radial direction R. The magnet 55 faces the thin-walled portion 14 of the thrust plate 12. The inner diameter of the magnet 55 is larger than the diameter of the first through hole 16.

[0044] Referring to Figures 6 to 8, in the second modified embodiment, the position of the magnet 55 in the thrust direction T is adjustable. That is, the magnet gap g, which is the distance between the front surface of the thrust bearing sleeve 50 and the front surface of the magnet 55 in the thrust direction T, is adjustable.

[0045] Referring to Figure 6, in the first example of the second modification, the magnet 55 is screwed into the case 57, and the magnet 55 is movable in the thrust direction T relative to the case 57. Therefore, the position of the magnet 55 in the thrust direction T is adjustable, and the magnet gap g is adjustable.

[0046] Referring to Figure 7, in the second example of the second modification, the hydrostatic bearing spindle 1 further comprises a spacer 80. The spacer 80 contacts the case 57 and the rear surface of the magnet 55. By changing the thickness of the spacer 80, the position of the magnet 55 in the thrust direction T is adjustable, and the magnet gap g is adjustable. For example, the thickness of the spacer 80 positioned between the case 57 and the magnet 55 can be changed by selecting one spacer 80 from a plurality of spacers 80 having different thicknesses.

[0047] Referring to Figure 8, in the third example of the second modification, the hydrostatic bearing spindle 1 further comprises a spacer 80 and a cover 82. The case 57 includes an inner wall 57w that protrudes into the second through-hole 58 from the inner circumferential surface of the second through-hole 58. The inner wall 57w is formed in the portion of the case 57 that is close to the thrust plate 12. The magnet 55 is positioned on the inner circumferential surface of the second through-hole 58. The spacer 80 is in contact with the rear surface of the inner wall 57w and the front surface of the magnet 55. By changing the thickness of the spacer 80, the position of the magnet 55 in the thrust direction T is adjustable, and the magnet gap g is adjustable. The cover 82 is attached to a portion of the inner circumferential surface defining the second through-hole 58 and the inner wall 57w. The cover 82 supports the magnet 55 and the spacer 80. The cover 82 is provided with a through-hole 83. The through-hole 83 communicates with the first through-hole 16. The through-hole 83 may be coaxial with the first through-hole 16. The diameter of the through-hole 83 is smaller than the diameter of the second through-hole 58. The through-hole 83 is located inward in the radial direction R compared to the second through-hole 58.

[0048] Referring to Figure 9, in a third modified embodiment, the thrust bearing sleeve 50 is elastically supported by the case 57. Specifically, the hydrostatic bearing spindle 1 further comprises elastic members 85 and 86. The elastic members 85 and 86 are, for example, O-rings. The elastic members 85 and 86 are positioned between the case 57 and the thrust bearing sleeve 50, and elastically support the thrust bearing sleeve 50 relative to the case 57. Elastic member 85 is positioned between the rear surface of the thrust bearing sleeve 50 and the case 57, and elastically supports the thrust bearing sleeve 50 relative to the case 57 in the thrust direction T. Elastic member 86 is positioned between the outer surface of the thrust bearing sleeve 50 and the case 57, and elastically supports the thrust bearing sleeve 50 relative to the case 57 in the radial direction R.

[0049] Referring to Figures 10 to 19, in the fourth modified example of the embodiment, the radial bearing 24 and the thrust bearing 53 may be self-reducing hydrostatic bearings, porous hydrostatic bearings, orifice hydrostatic bearings, or composite hydrostatic bearings.

[0050] For example, the radial bearing 24 and the thrust bearing 53 may be self-reducing hydrostatic bearings as shown in Figures 10 and 11. Specifically, the diameter of the portion of the first nozzle 22 that is close to the radial bearing clearance 23 is smaller than the diameter of the portion of the first nozzle 22 that is distal to the radial bearing clearance 23. The diameter of the portion of the second nozzle 51 that is close to the thrust bearing clearance 52 is smaller than the diameter of the portion of the second nozzle 51 that is distal to the thrust bearing clearance 52.

[0051] The radial bearing 24 and thrust bearing 53 may be porous throttling type hydrostatic bearings as shown in Figures 12 and 13. Specifically, the radial bearing sleeve 21 and thrust bearing sleeve 50 are formed of porous material. A groove 88 may be provided in the portion of the radial bearing sleeve 21 facing the first bearing gas supply passage 30. The first bearing gas spreads in the groove 88 and is supplied more uniformly throughout the porous material. A groove 89 may be provided in the portion of the thrust bearing sleeve 50 facing the second bearing gas supply passage 65. The second bearing gas spreads in the groove 89 and is supplied more uniformly throughout the porous material.

[0052] The radial bearing 24 and thrust bearing 53 may be orifice-type hydrostatic bearings as shown in Figures 14 and 15. Specifically, the first nozzle 22 includes a pocket 90 facing the radial bearing clearance 23 and an orifice hole 91 provided at the bottom of the pocket 90. The diameter of the orifice hole 91 is smaller than the diameter of the pocket 90. The second nozzle 51 includes a pocket 92 facing the thrust bearing clearance 52 and an orifice hole 93 provided at the bottom of the pocket 92. The diameter of the orifice hole 93 is smaller than the diameter of the pocket 92.

[0053] The radial bearing 24 and thrust bearing 53 may be composite throttling type hydrostatic bearings as shown in Figures 16 to 19. A composite throttling type hydrostatic bearing is a hydrostatic bearing that combines a throttling hole and a groove provided so as to overlap the throttling hole.

[0054] Referring to Figure 16, a groove 88 may be formed so as to overlap the aperture hole 91. For example, a groove 88 may be formed on the inner diameter surface of the radial bearing sleeve 21 so as to overlap the aperture hole 91. Referring to Figure 17, a groove 89 may be formed so as to overlap the aperture hole 93. For example, a groove 89 may be formed on the end surface of the thrust bearing sleeve 50 so as to overlap the aperture hole 93.

[0055] Referring to Figure 18, a first composite thrombus may be formed on the first nozzle 22 and the shaft portion 11. For example, the first nozzle 22 may have a thrombus hole 91 and a groove 94. The groove 94 is formed on the outer circumferential surface of the shaft portion 11. The groove 94 functions to distribute pressure over a wide area. Therefore, the first nozzle 22 and the shaft portion 11 form a first composite thrombus type hydrostatic bearing, which is a combination of a thrombus hole and a groove. Referring to Figure 19, a second composite thrombus may be formed on the second nozzle 51 and the thrust plate 12. For example, the second nozzle 51 may have a thrombus hole 93 and a groove 95. The groove 95 is formed on the rear surface of the thrust plate 12. The groove 95 functions to distribute pressure over a wide area. Therefore, the second nozzle 51 and the thrust plate 12 form a second composite thrombus type hydrostatic bearing, which is a combination of a thrombus hole and a groove.

[0056] The effects of the hydrostatic bearing spindle 1 of this embodiment will be explained. The hydrostatic bearing spindle 1 of this embodiment comprises a rotating shaft 10, a radial bearing sleeve 21, a thrust bearing sleeve 50, and a magnet 55. The rotating shaft 10 includes a shaft portion 11 extending in the thrust direction T, a thrust plate 12 extending from the shaft portion 11 in the radial direction R intersecting the thrust direction T, and turbine blades 15 provided on the thrust plate 12. The radial bearing sleeve 21 is positioned opposite the shaft portion 11 in the radial direction R. The thrust bearing sleeve 50 is positioned opposite the thrust plate 12 in the thrust direction T. The magnet 55 attracts the rotating shaft 10 in the thrust direction T. A radial bearing 24 supporting the shaft portion 11 in the radial direction R is formed between the shaft portion 11 and the radial bearing sleeve 21. A thrust bearing 53 supporting the rotating shaft 10 in the thrust direction T is formed between the thrust plate 12 and the thrust bearing sleeve 50. The thrust bearing sleeve 50 and the magnet 55 are positioned in the thrust direction T on the opposite side of the thrust plate 12 from the radial bearing sleeve 21. The distance L in the thrust direction T from the thrust bearing 53 to the center C1 of the radial bearing 24 in the thrust direction T is greater than the diameter D of the center C2 of the thrust bearing 53 in the radial direction R.

[0057] Since the thrust bearing sleeve 50 and the magnet 55 are positioned on the opposite side of the thrust plate 12 from the radial bearing sleeve 21 in the thrust direction T, the area of ​​the radial bearing 24 can be increased. As a result, the load-bearing characteristics of the hydrostatic bearing spindle 1 are improved. Furthermore, since the distance L in the thrust direction T from the thrust bearing 53 to the center C1 of the radial bearing 24 in the thrust direction T is greater than the diameter D of the center C2 of the thrust bearing 53 in the radial direction R, the radial bearing 24 can be made longer in the thrust direction T. As a result, the load-bearing characteristics of the hydrostatic bearing spindle 1 are improved.

[0058] In the hydrostatic bearing spindle 1 of this embodiment, through holes (first through holes 16) extending in the thrust direction T are provided in the shaft portion 11 and the thrust plate 12. The thrust bearing 53 surrounds the through holes.

[0059] Therefore, a paint spray nozzle 78 and the like can be placed inside the through hole (first through hole 16). The hydrostatic bearing spindle 1 can be applied to electrostatic painting machines and the like. In addition, since the thrust bearing 53 surrounds the through hole, the thrust bearing 53 can prevent turbine gas from flowing into the first through hole 16 through the thrust bearing gap 52. When the hydrostatic bearing spindle 1 is used in an electrostatic painting machine, deterioration of painting quality can be prevented.

[0060] In the hydrostatic bearing spindle 1 of this embodiment, the magnet 55 is positioned inward in the radial direction R from the thrust bearing sleeve 50.

[0061] Therefore, the size of the magnet 55 can be reduced. The size and cost of the hydrostatic bearing spindle 1 are also reduced.

[0062] In the hydrostatic bearing spindle 1 of this embodiment, the magnet 55 is positioned outside the thrust bearing sleeve 50 in the radial direction R.

[0063] Therefore, the load-bearing characteristics of the hydrostatic bearing spindle 1 are improved. In the hydrostatic bearing spindle 1 of this embodiment, the magnet 55 has a ring shape.

[0064] Therefore, a paint spray nozzle 78 and the like can be placed inside the through-hole of the magnet 55. The hydrostatic bearing spindle 1 can be applied to electrostatic painting machines and the like.

[0065] In the hydrostatic bearing spindle 1 of this embodiment, the position of the magnet 55 in the thrust direction T is adjustable.

[0066] Therefore, the attractive force of the rotating shaft 10 by the magnet 55 can be adjusted. The size of the thrust bearing clearance 52 can be appropriately adjusted. An appropriate thrust bearing 53 can be formed according to the pressure of the second bearing gas supplied to the hydrostatic bearing spindle 1 and the application of the hydrostatic bearing spindle 1.

[0067] The hydrostatic bearing spindle 1 of this embodiment further comprises a case 57 that houses a thrust bearing sleeve 50 and a magnet 55. The thrust bearing sleeve 50 is fixed to the case 57.

[0068] Therefore, the thrust bearing sleeve 50 and the magnet 55 are mechanically protected by the case 57.

[0069] The hydrostatic bearing spindle 1 of this embodiment further comprises a case 57 that houses a thrust bearing sleeve 50 and a magnet 55. The thrust bearing sleeve 50 is elastically supported by the case 57.

[0070] Therefore, the thrust bearing sleeve 50 and the magnet 55 are mechanically protected by the case 57. In addition, because the thrust bearing sleeve 50 is elastically supported by the case 57, the thrust bearing sleeve 50 can more easily follow changes in the orientation of the rotating shaft 10. Even when loads caused by gyroscopic moment and vibration of the rotating shaft act on the rotating shaft 10, the rotating shaft 10 can rotate more stably.

[0071] The hydrostatic bearing spindle 1 of this embodiment comprises a housing 25 that accommodates a radial bearing sleeve 21, a cover 27 that covers the housing 25, and a plurality of O-rings 41, 42, 43, and 44. The plurality of O-rings 41, 42, 43, and 44 are positioned between the housing 25 and the cover 27, and elastically support the housing 25 with respect to the cover 27. In the thrust direction T, at least one of the plurality of O-rings 41, 42, 43, and 44 (O-ring 43) is positioned between the center C1 of the radial bearing 24 and the center of gravity G1 of the rotating shaft 10.

[0072] Therefore, at least one O-ring (O-ring 43) can be positioned closer to the center of gravity G1 of the rotating shaft 10. At least one O-ring can reduce the influence of gyroscopic moment and vibration of the rotating shaft 10 on the radial bearing 24 and thrust bearing 53. The rotating shaft 10 can rotate more stably.

[0073] In the hydrostatic bearing spindle 1 of this embodiment, the shaft portion 11 includes a first end portion 11a on which a thrust plate 12 is provided, and a second end portion 11b opposite to the first end portion 11a. A bell cup mounting portion 18 is formed on the second end portion 11b.

[0074] Therefore, the load-bearing characteristics of the hydrostatic bearing spindle 1 are improved. The hydrostatic bearing spindle 1 can be applied to an electrostatic painting machine.

[0075] The hydrostatic bearing spindle 1 of this embodiment further includes a bell cup 19 attached to the bell cup mounting portion 18.

[0076] Therefore, the hydrostatic bearing spindle 1 can be applied to an electrostatic painting machine. The hydrostatic bearing spindle 1 of this embodiment comprises a housing 25 that accommodates a radial bearing sleeve 21, a cover 27 that covers the housing 25, and a plurality of O-rings 41, 42, 43, and 44. The plurality of O-rings 41, 42, 43, and 44 are positioned between the housing 25 and the cover 27, and elastically support the housing 25 with respect to the cover 27. In the thrust direction T, at least one of the plurality of O-rings 41, 42, 43, and 44 (O-ring 43) is positioned between the center C1 of the radial bearing 24 and the overall center of gravity G2 of the rotating shaft 10 and the bell cup 19.

[0077] Therefore, at least one O-ring (O-ring 43) can be positioned closer to the overall center of gravity G2 of the rotating shaft 10 and the bell cup 19. When the bell cup 19 is attached to the rotating shaft 10, at least one O-ring can reduce the effect of the gyroscopic moment and vibration of the rotating shaft 10 on the radial bearing 24 and the thrust bearing 53. The rotating shaft 10 and the bell cup 19 as a whole can rotate more stably.

[0078] The hydrostatic bearing spindle 1 of this embodiment comprises a housing 25 that accommodates a radial bearing sleeve 21, a cover 27 that covers the housing 25, and a plurality of O-rings 41, 42, 43, and 44. The plurality of O-rings 41, 42, 43, and 44 are positioned between the housing 25 and the cover 27, and elastically support the housing 25 with respect to the cover 27. In the thrust direction T, at least one of the plurality of O-rings 41, 42, 43, and 44 (O-ring 44) is positioned between the center of gravity G1 of the rotating shaft 10 and the center of gravity G3 of the bell cup 19.

[0079] Therefore, even if a vibration load is applied to the bell cup mounting portion 18 side (the side of the second end portion 11b) of the hydrostatic bearing spindle 1, at least one O-ring (O-ring 44) can reduce the effect of the load on the radial bearing 24 and the thrust bearing 53. The entire rotating shaft 10 and bell cup 19 can rotate more stably.

[0080] In the hydrostatic bearing spindle 1 of this embodiment, the radial bearing 24 and thrust bearing 53 are hydrostatic bearings of the self-forming throttling type, porous throttling type, or orifice throttling type, or composite throttling type.

[0081] Therefore, the load-bearing characteristics of the hydrostatic bearing spindle 1 are improved. The embodiments and variations thereof disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than the foregoing description and is intended to include all modifications in the sense and scope equivalent to the claims. [Explanation of Symbols]

[0082] 1 Hydrostatic bearing spindle, 10 Rotating shaft, 11 Shaft section, 11a First end, 11b Second end, 12 Thrust plate, 13 Thick section, 14 Thin section, 15 Turbine blade, 16 First through hole, 17 Detected section, 17a First region, 17b Second region, 18 Bell cup mounting section, 19 Bell cup, 20 Housing assembly, 21 Radial bearing sleeve, 22 First nozzle, 23 Radial bearing clearance, 24 Radial bearing, 25 Housing, 27 Cover, 30 First bearing gas supply passage, 31 First bearing gas inlet, 33 Turbine gas exhaust passage, 34 Turbine gas exhaust port, 35 Space, 41, 42, 43, 44 O-rings, 50 Thrust bearing sleeve, 51 Second nozzle, 52 Thrust bearing clearance, 53 Thrust bearing, 55 Magnet, 57 Case, 57w inner wall, 58 second through hole, 59 third through hole, 60 turbine gas supply passage, 61 turbine gas inlet, 62 turbine nozzle, 65 second bearing gas supply passage, 66 second bearing gas inlet, 70 spindle holder, 71 housing section, 72 bearing gas supply passage, 73 turbine gas supply passage, 74 turbine gas exhaust passage, 75 paint supply passage, 76 rotation sensor, 77 sensor holder, 78 paint spray nozzle, 80 spacer, 82 lid, 83 through hole, 85, 86 elastic member, 88, 89 groove, 90, 92 pocket, 91, 93 throttling hole, 94, 95 groove.

Claims

1. A rotating shaft including a shaft portion extending in the thrust direction, a thrust plate extending radially from the shaft portion intersecting the thrust direction, and turbine blades provided on the thrust plate, A radial bearing sleeve is arranged opposite the shaft portion in the radial direction, A thrust bearing sleeve is positioned opposite the thrust plate in the thrust direction, The system includes a magnet that attracts the rotating shaft in the thrust direction, A radial bearing supporting the shaft portion in the radial direction is formed between the shaft portion and the radial bearing sleeve. A thrust bearing supporting the rotating shaft in the thrust direction is formed between the thrust plate and the thrust bearing sleeve. The thrust bearing sleeve and the magnet are positioned in the thrust direction on the side opposite to the radial bearing sleeve with respect to the thrust plate. A hydrostatic bearing spindle in which the distance in the thrust direction from the thrust bearing to the center of the radial bearing in the thrust direction is greater than the diameter of the center of the thrust bearing in the radial direction.

2. Through holes extending in the thrust direction are provided in the shaft portion and the thrust plate, The thrust bearing is a hydrostatic bearing spindle according to claim 1, surrounding the through hole.

3. The hydrostatic bearing spindle according to claim 1 or 2, wherein the magnet is positioned inward in the thrust direction from the thrust bearing sleeve.

4. The hydrostatic bearing spindle according to claim 1 or 2, wherein the magnet is positioned outside the radial direction R relative to the thrust bearing sleeve.

5. The hydrostatic bearing spindle according to claim 1 or claim 2, wherein the magnet has a ring shape.

6. The hydrostatic bearing spindle according to claim 1 or claim 2, wherein the position of the magnet in the thrust direction is adjustable.

7. The case further comprises the thrust bearing sleeve and the magnet, The hydrostatic bearing spindle according to claim 1 or claim 2, wherein the thrust bearing sleeve is fixed to the case.

8. The case further comprises the thrust bearing sleeve and the magnet, The hydrostatic bearing spindle according to claim 1 or claim 2, wherein the thrust bearing sleeve is elastically supported in the case.

9. A housing for accommodating the radial bearing sleeve, A cover that covers the aforementioned housing, Equipped with multiple O-rings, The plurality of O-rings are positioned between the housing and the cover, and elastically support the housing relative to the cover. The hydrostatic bearing spindle according to claim 1 or 2, wherein in the thrust direction, at least one of the plurality of O-rings is positioned between the center of the radial bearing and the center of gravity of the rotating shaft.

10. The shaft portion includes a first end to which the thrust plate is provided and a second end opposite to the first end, The hydrostatic bearing spindle according to claim 1 or claim 2, wherein a bell cup mounting portion is formed at the second end.

11. The hydrostatic bearing spindle according to claim 10, further comprising a bell cup attached to the bell cup mounting portion.

12. A housing for accommodating the radial bearing sleeve, A cover that covers the aforementioned housing, Equipped with multiple O-rings, The plurality of O-rings are positioned between the housing and the cover, and elastically support the housing relative to the cover. The hydrostatic bearing spindle according to claim 11, wherein in the thrust direction, at least one of the plurality of O-rings is positioned between the center of the radial bearing and the center of gravity of the rotating shaft and the bell cup as a whole.

13. A housing for accommodating the radial bearing sleeve, A cover that covers the aforementioned housing, Equipped with multiple O-rings, The plurality of O-rings are positioned between the housing and the cover, and elastically support the housing relative to the cover. The hydrostatic bearing spindle according to claim 11, wherein at least one of the plurality of O-rings is positioned between the center of gravity of the rotating shaft and the center of gravity of the bell cup in the thrust direction.

14. The hydrostatic bearing spindle according to claim 1 or claim 2, wherein the radial bearing and the thrust bearing are hydrostatic bearings of the self-reducing throttling type, hydrostatic bearings of the porous throttling type, hydrostatic bearings of the orifice throttling type, or hydrostatic bearings of the composite throttling type.

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