JP2011140983A - Fluid bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid bearing device for a rotary apparatus endurable against high rotation with a simple structure. <P>SOLUTION: This fluid bearing device includes a shaft hole member 1 having a bearing surface 1a of a predetermined width in the axial direction on an inner peripheral surface for partitioning a shaft hole, a shaft member 2 having a shaft surface 2a opposed to the bearing surface rotatably held by the shaft hole and a fluid supply means for supplying fluid between the bearing surface and the shaft surface. Both the bearing surface and the shaft surface are a side peripheral surface shape of a truncated cone shape, and the fluid supply means supplies the fluid in the axial direction between the bearing surface and the shaft surface. The bearing surface and the shaft surface are the side peripheral surface shape of the truncated cone shape, and since the fluid is supplied in the axial direction in these clearances, the shaft member 2 is energized to the axis of the shaft hole member 1, and can receive a load in the radial direction and a load in the axial direction by one mechanism, and a structurally simple rotary apparatus can be realized. The shaft member 2 has a turbine 8 on the axis, and rotates by a jet from a nozzle 6 of the shaft hole member 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing device.

  2. Description of the Related Art There are known bearing devices for use in machine tools such as a luter that are used for various processes by attaching a grindstone or a tool to a shaft that rotates at high speed, and for rotating equipment such as medical and dental instruments (handpieces). Among such rotating devices, there are those that use a motor for driving and those that rotate a turbine by compressed air. Also, the bearing receives a shaft by generating a fluid pressure when the shaft rotates by a rolling bearing such as a ball bearing or a dynamic pressure generating groove arranged in a herringbone shape or a V shape on the shaft or sleeve. There are sliding bearings such as a hydrodynamic bearing and a hydrostatic bearing that receives a shaft by supplying compressed air from the outside.

  Generally, grinding and cutting become easier as the grindstone and tool are rotated at a higher speed, the processing load can be reduced, and processing can be completed in a short time. For this reason, devices for rotating at high speed have been devised. Patent Document 1 discloses a structure in which a main shaft driven by a motor is supported by air. Patent Document 2 discloses a structure in which a turbine is rotated with compressed air and axial and radial directions are received by a hydrostatic bearing. Patent Document 3 discloses a structure in which a radial direction of a turbine rotating with a fluid is received by a hydrostatic bearing, and a convex spherical surface or the like is brought into contact with a plane in the axial direction.

  However, the above-described conventional example has a problem that the structure is complicated (Patent Documents 1 and 2) or has a very short life (Patent Document 3).

JP-A-11-117939 JP 2001-20701 A JP-A-6-292690

  For applications where a small cutting edge or grindstone is attached to the tip, a machine that rotates at high speed is held with one hand, and fine processing is performed while visually checking the object, a simple structure that is small and lightweight has been required. . Even now, there is a strong demand for such rotating devices for the above-mentioned uses, specifically glasswork, deburring after metal processing, chamfering after processing, hobby work, medical and dental treatment. .

  An object of the present invention is to provide a hydrodynamic bearing device for a rotating device that has a simple structure and can withstand high rotation.

  In order to solve the above-mentioned problems, the present inventor diligently studied a fluid bearing, and as a result, reached the present invention. The hydrodynamic bearing device of the present invention has a shaft hole member having a bearing surface having a predetermined width in the axial direction on an inner peripheral surface defining the shaft hole, and a shaft surface that is rotatably held in the shaft hole and faces the bearing surface. A fluid dynamic bearing device having a shaft member and a fluid supply means for supplying a fluid between the bearing surface and the shaft surface, both of the bearing surface and the shaft surface are in the shape of a frustoconical side surface, and the fluid supply means Is characterized by supplying fluid in the axial direction between the bearing surface and the shaft surface. The bearing surface and the shaft surface of the hydrodynamic bearing device of the present invention are frustoconical side surfaces, and fluid is supplied to the gap between them in the axial direction, so that the shaft member is biased to the shaft center of the shaft hole member. The load in the radial direction and the load in the axial direction can be received by one mechanism, and a rotating device with a simple structure can be realized.

  The shaft hole member has at least one set of bearing surfaces, each of which has a pair of two cones whose apex directions are opposite to each other. The shaft member has at least one set of shaft surfaces respectively opposed to the one set of bearing surfaces. It is good to have. If it carries out like this, manufacture of a shaft hole member and a shaft member will become easy, and it will also become easy to assemble a bearing device.

  The fluid may be a gas. High speed rotation can be realized, and the influence of exhaust can be avoided by selecting an appropriate gas, particularly when the workpiece does not like oxidation.

  The gas may be air. A pressure fluid can be easily generated by a compressor or the like.

  It is desirable that the angle formed between the bearing surface and the shaft surface facing the bearing surface with respect to the axial direction of the shaft member on the cross section in the axial direction is the same. With such a structure, a good bearing can be formed.

  The minimum inner diameter of the bearing surface is preferably smaller than the maximum outer diameter of the shaft surface. With such a configuration, the areas of the bearing surface and the shaft surface can be increased, and the load per unit area can be reduced. Therefore, the bearing device can withstand a large load even with a small size.

  There may be at least four bearing surfaces and shaft surfaces in the axial direction. By carrying out like this, it can be set as a small bearing apparatus which receives the load of a radial direction, and the load of an axial direction with one mechanism.

  The shaft member may have a turbine that is driven by a fluid on the same axis, and the shaft hole member may have a nozzle port that ejects fluid toward the turbine. With such a structure, a rotary drive device can be easily obtained.

  In the hydrodynamic bearing device, since both the bearing surface and the shaft surface are frustoconical side circumferential surfaces, there is no need to provide separate bearings in the radial direction and the axial direction, and a long-life and simple structure can be obtained. it can.

It is the cutting part end view cut by the central axis which shows the fluid dynamic bearing device of the present invention. It is sectional drawing of the radial direction cut | disconnected by the nozzle part which shows the hydrodynamic bearing apparatus of this invention. It is a cutting part end view which shows a mode that the turbine was provided in the bearing apparatus of this invention. FIG. 4 is a radial cross-sectional view cut at the nozzle portion of FIG. 3 to show the relationship between the turbine and the nozzle. It is a cutting part end view which shows another Example of this invention. It is a three-dimensional schematic diagram of an outer ring and an inner ring showing a state of assembling. It is sectional drawing of the radial direction cut | disconnected by the nozzle part of FIG. 5, which shows the relationship between a turbine, a nozzle, and a sub nozzle. (The outer ring collar is omitted) It is a schematic diagram which shows a mode that the dynamic-pressure generation | occurrence | production groove | channel was provided in the inner ring. It is a cutting part end view which shows another Example made into the dynamic pressure fluid bearing. It is a schematic diagram which shows the example of the machine tool which has a bearing of this invention.

  FIG. 1 is a cut end view showing an embodiment of the present invention. The hydrodynamic bearing device of the present embodiment has a cylindrical shaft hole member 1 having an inclined surface 1a on the inner peripheral side of both end portions and a nozzle 6 at the center portion, a shaft 3 inside the shaft hole member 1, The shaft member 2 includes a first flange 4 and a second flange 5 that protrude in the radial direction and have a truncated cone shape (or frustoconical shape) on one side in the axial direction.

  The inclined surface 1 a of the shaft hole member 1 has a truncated conical concave surface so as to correspond to the truncated conical convex surface of the flange portion of the shaft member 2. In this embodiment, the frustoconical side circumferential surface (conical concave surface) portion of the shaft hole member 1 corresponds to the bearing surface of the present invention, and the frustoconical side circumferential surface of the shaft member 2 facing the bearing surface. The shape portion corresponds to the axial surface of the present invention. Therefore, in FIG. 1, there are two bearing surfaces 1a and two shaft surfaces 2a. The bearing surface 1a and the shaft surface 2a have the same angle with respect to the axial direction of the shaft member 2 on the cross section. In the first embodiment, the angle is set to 30 degrees, but there is a relationship that the effect of supporting the load in the axial direction is reduced at a small angle, and the effect of supporting the load in the radial direction is reduced at a large angle. It is preferable to select in the range of 10 to 80 degrees depending on the application. In addition, when compressed air is not supplied, although the bearing surface 1a and the shaft surface 2a may partly contact, each figure represents the state by which compressed air is supplied.

  The hydrodynamic bearing device is supplied with compressed air from the outside through the nozzle 6 of the shaft hole member 1. Although simplified in FIG. 1, as shown in FIG. 2, the nozzle 6 is offset so that its extension does not pass through the center of the shaft hole member 1. Therefore, the compressed air is guided by the inner periphery of the shaft hole member 1 and rotates in the space between the shaft hole member 1 and the shaft member 2. In the axial direction, the compressed air is divided into a front end side and a rear end side, and passes through a space in which the shaft hole member 1 and the shaft 3 are parallel and opposed in FIG. 1, and the bearing surface 1 a of the shaft hole member 1 and the shaft member 2. A narrow space consisting of the axial surface 2a is reached. At this time, if the bearing surface 1a and the shaft surface 2a are displaced from each other and partly close to each other, the bearing surface 1a and the shaft surface 2a have different curvatures in cross section. The compressed air rotating around the shaft member 2 is guided and acts to separate the bearing surface 1a and the shaft surface 2a. As a result, the center of the shaft member 2 is urged to a position substantially coincident with the center of the shaft hole member 1, and the pressure of the compressed air becomes substantially equal in the circumferential direction and is stably held. In FIG. 2, there are four nozzles 6 that are equally arranged, but the center of the shaft member 2 may be urged toward the center of the shaft hole member 1, and the number and arrangement are not limited. In the hydrodynamic bearing device of the present embodiment, the shaft member 2 is biased to the shaft center of the shaft hole member 1 by supplying compressed air through the nozzle 6. Even if the shaft member 2 is not rotating, the shaft member 2 is not in contact with the shaft hole member 1. Therefore, when the shaft member 2 is rotated by hand, the shaft member 2 continues to rotate considerably long.

  Further, since the nozzle 6 is provided substantially at the center between the two bearing surfaces 1a and the shaft surface 2a at both ends, the distance between the bearing surface 1a and the shaft surface 2a at both ends is equal in the axial direction as well as in the radial direction. Act to be. Thus, the hydrodynamic bearing of the present invention supports a radial load and an axial load by a single mechanism. In particular, it is superior in durability compared to the one that supports point contact in the axial direction.

  Furthermore, the bearing device can be applied to a rotational drive device. A state in which the turbine 8 is provided on the shaft 3 is shown in FIG. 3 which is a cut end view, and a radial sectional view of the central portion of FIG. 3 is shown in FIG. Note that the proportional relationship of FIG. 4 is different from that of FIG. The nozzle 6 is provided so that its extension does not pass through the center of the shaft member, but is shown in a simplified manner in FIG. The turbine 8 is a radial flow turbine. If the relationship between the turbine 8 and the nozzle 6 is as shown in FIG. 4, the turbine 8 can be rotated.

  Exhaust gas that has rotated the turbine 8 is divided into a front end side and a rear end side, passes through a space in which the shaft hole member 1 and the shaft 3 are parallel to each other in FIG. 3, and the bearing surface 1 a of the shaft hole member 1 and the shaft member. It reaches a narrow space composed of two axial surfaces 2a. The exhaust gas acts to separate the bearing surface 1a and the shaft surface 2a, which are parallel to each other in this cross section, in the radial direction, forms a fluid bearing, and is discharged from the discharge port 7 to the outside. By arranging each component as shown in FIG. 3, a fluid that separates both surfaces between the bearing surface 1 a and the shaft surface 2 a and a fluid that rotates the turbine 8 are rotated with a common nozzle 6 and a discharge port 7. A drive device is obtained. By doing in this way, processing of a dedicated nozzle or exhaust port can be omitted, and the structure of the piping can be simplified as a whole of the rotary drive device, contributing to miniaturization. Since the shaft member 2 rotates together with the turbine 8, a predetermined application can be achieved by providing a collet chuck (not shown) on the tip side and attaching a tool, a grindstone, or the like.

  With the above configuration, since the bearing device is a fluid bearing, there is no fear of heat generation in the bearing portion, and since a fluid is used for driving, there is no problem of heat generation in the driving portion as in the case of using a motor. Can provide.

  As an example of the assembling method, a cylindrical shaft hole member 1 whose bearings are machined on the inner surfaces of both ends is inserted in advance with a shaft 3 fixed with a turbine 8 and a first flange 4 by a predetermined method. The two flanges 5 are inserted into the shaft 3 and fastened and fixed with a screw portion (not shown) provided at the end of the shaft 3 with a lock nut 9, but this is not particularly limited.

  In FIGS. 1 and 3, the shaft 3, the first flange 4, and the second flange 5 are separate from each other in the shaft member 2, but the shaft 3 and the first flange 4 may be integrally formed. When the shaft member 2 is made, the first flange 4 can be made at the same time, and there is an advantage that the number of steps for fixing the first flange 4 can be reduced. The material is not particularly limited.

  This structure can also be applied to a case where the fluid is a liquid such as oil, water, or antifreeze, as long as the path of the discharged fluid is secured. For example, in the case where water is circulated by a pump in a fish tank, the rotation of the turbine 8 is visually confirmed if the rotary drive device in which the shaft hole member 1 is formed of a transparent resin is installed in the path in the tank. By this, you can check the circulation of water and you can also decorate it. Moreover, application to a hydroelectric generator is also possible.

  An embodiment of a rotary drive device having a bearing device capable of withstanding a large load by increasing the number of bearing surfaces and shaft surfaces will be described. A cut end view of this embodiment is shown in FIG. The shaft hole member 1 includes a housing 10 and an outer ring 11 fixed to the housing 10 and having a bearing surface 1a. The shaft member 2 includes a shaft 3, an inner ring 12 fixed to the shaft 3, and an end inner ring 13. Outer rings 11 and inner rings 12 are alternately arranged on the front end side and rear end side of the turbine 8 fixed to the shaft 3.

  As can be seen from FIG. 5 and FIG. 6, which is a three-dimensional schematic diagram, the bearing surface 1 a is an inclined surface of the outer ring 11, and the shaft surface 2 a is an inclined surface of the inner ring 12 and the end inner ring 13. As in the first embodiment, each of them has a frustoconical side surface shape, the bearing surface 1a is a conical concave surface, and the shaft surface 2a is a conical surface (conical convex surface). In this embodiment, the frustoconical side circumferential surface (conical concave surface) portion excluding the surface of the outer ring 11 that does not face the inner ring 12 corresponds to the bearing surface of the present invention, and the inner ring 12 that faces the bearing surface, A portion of the end-side inner ring 13 that has a truncated cone-shaped side circumferential surface (conical convex surface) corresponds to an axial surface. Therefore, in FIG. 5, the number of the bearing surfaces 1a and the shaft surfaces 2a is ten, but the number is not limited, and can be increased or decreased according to the overall dimensions and the like.

  As shown in FIG. 6, the inner ring 12 has a shape similar to an abacus bead when the size is ignored, and the outer ring 11 has a shape that fills a space when two inner rings 12 are arranged in the axial direction. As can be seen from FIG. 5, the end inner ring 13 has a shape in which the inner ring 12 is halved in the axial direction, and the outer diameter and the angle of the inclined surface are the same as those of the inner ring 12. As can be seen from FIGS. 5 and 6, the smallest inner diameter of the outer ring 11, that is, the minimum inner diameter of the bearing surface 1a is smaller than the largest part of the inner ring 12 and the inner ring 13 for the end, that is, the maximum outer shape of the shaft surface 2a. It has become. With such a configuration, the areas of the bearing surface 1a and the shaft surface 2a can be increased, and the load per unit area can be reduced. Therefore, a bearing device that can withstand a large load can be obtained.

  Both the outer ring 11 and the inner ring 12 have two inclined surfaces, and the end inner ring 13 has one inclined surface. In the present embodiment, the angles of the inclined surfaces of the outer ring 11, the inner ring 12, and the end inner ring 13 are set to 45 degrees with respect to the axial direction in the cross section, but an angle of 10 degrees to 80 degrees is appropriately selected depending on the application. Is preferred. In this embodiment, the two inclined surfaces of the outer ring 11 and the inner ring 12 have the same angle. However, if the bearing surface 1a and the shaft surface 2a facing each other have the same angle, The angles may be different from each other, and an angle of 10 to 80 degrees is appropriately selected.

  An example of an assembly method will be described. First, the end inner ring 13 is inserted into the shaft 3 with the fixing flange 14 and abuts against the fixing flange 14. This is placed in the housing 10 so as to be on the front end side, and then the outer ring 11 is inserted to the abutting portion of the housing 10. Next, a predetermined number of inner rings 12 and outer rings 11 are alternately inserted from the rear end side, an inner ring collar 15 for adjusting dimensions is inserted, then a turbine 8, an inner ring collar 15 and an outer ring collar 16 are inserted, and the outer ring 11 and again are inserted. A predetermined number of inner rings 12 are alternately set, and an inner ring 13 for an end and a fixing flange 14 are inserted and fastened with a screw nut (not shown) provided at the end of the shaft 3 with a lock nut 9 and fixed. The outer ring 11 is fixed by fastening the fixing ring 17 with a screw portion (not shown) provided at the end of the housing 10. The positions of the outer rings 11 and the inner rings 12 are determined by abutting each other.

  Next, the operation will be described. First, when compressed air is sent from the sub nozzle 18, the shaft 3 rotates. The rotation by the sub-nozzles 18 is such that the angle at which the compressed air strikes the blades of the turbine 8 is small as can be seen from FIG. Therefore, the blades of the turbine 8 are not efficiently rotated, and the rotation is relatively slow. This rotation is called preliminary rotation. By confirming this preliminary rotation, it can be confirmed that the bearing surface 1a and the shaft surface 2a are separated to form a fluid bearing. Next, when the compressed air is sent from the nozzle 6, the nozzle 6 is arranged at the center in the width direction of the turbine 8 as can be seen from FIG. 5, and the compressed air has a large angle at the blades of the turbine 8 as can be seen from FIG. 7. In order to efficiently rotate the turbine 8, the power of the preliminary rotation is overcome and the turbine 8 starts to rotate in the direction opposite to the preliminary rotation. This rotation is called main rotation. In FIG. 5, the nozzle 6 and the sub nozzle 18 are shown to be in the same phase position, but the phases of both nozzles may be shifted as shown in FIG. After the main rotation starts, the supply of compressed air from the sub nozzle 18 may be stopped.

  When stopping the rotation, the supply of compressed air from the nozzle 6 is stopped, and at the same time, the compressed air is sent from the sub nozzle 18, or the compressed air is supplied from the sub nozzle 18 and then the supply from the nozzle 6 is stopped. To do. If the compressed air is not supplied, the outer ring 11 and the inner ring 12 cannot be kept in a non-contact state, and when rotating at a high speed, both of them may be seized and damaged. The outer ring 11 and the inner ring 12 can be prevented from coming into contact with the compressed air from the sub nozzle 18. Furthermore, since the compressed air from the sub nozzle 18 is directed to rotate in the direction opposite to the main rotation by the compressed air from the nozzle 6 as described above, it acts as a brake and the time required for stopping can be shortened. Since the preliminary rotation by the sub nozzle 18 is a slow rotation as described above, even if the compressed air is stopped after the preliminary rotation, it is not easily damaged. Furthermore, if the outer ring 11, the inner ring 12, and the end inner ring 13 are made of metal, a hard film or a lubricating film may be provided on the surface by plating, CVD, electrodeposition coating, or the like.

  When the nozzle 6 and the sub nozzle 18 are slightly inclined in the axial direction, the exhaust becomes smooth. In this case, it is preferable that the angle and the number of the one inclined to the front end side and the one inclined to the rear end side are equal.

  The fluid supply source is not particularly limited, but in the case of this embodiment, compressed air is supplied by a compressor (not shown), a regulator with a filter is arranged between the compressor and the nozzle to remove oil mist, and the pressure fluctuation is reduced. I tried to make it smaller.

  If the workpiece does not like oxidation or if there are concerns about the harmful effects of water vapor, use an appropriate gas such as nitrogen gas instead of compressed air in consideration of the effects of exhaust. .

  An example of a machine tool to which the above rotary drive device is applied is shown in FIG. A grindstone 25 with a shaft is attached to the collet chuck 24, pipes (not shown) to the nozzle 6 and the sub nozzle 18 are provided inside, and a sub nozzle pipe 26 and a nozzle pipe 27 are connected to the rear end side.

  As another embodiment, as shown in FIG. 8, a dynamic pressure generating inner ring 20 provided with a known dynamic pressure generating groove 19 or a similar inner ring 21 for generating dynamic pressure is used to constitute a rotary drive device. Also good. In the present embodiment, the frustoconical side circumferential surface (conical concave surface) portion of the outer ring 11 excluding the surface not facing the dynamic pressure generating inner ring 20 corresponds to the bearing surface of the present invention and faces the bearing surface. The portions of the frustoconical side circumferential surface (conical convex surface) of the inner ring 20 for generating dynamic pressure and the inner ring 21 for generating dynamic pressure correspond to the shaft surface. Further, in FIG. 8, the dynamic pressure generating groove 19 is provided in the inner ring 20, but the dynamic pressure generating groove is provided in at least one of the inner ring and the outer ring. In these cases, as shown in FIG. 9 which is a cut end view, the compressed air is discharged from the turbine exhaust port 23 appropriately provided in the housing 10, and the compressed air is subjected to dynamic pressure on the bearing surface 1a and the shaft surface 2a. Do not affect.

  Compressed air is used to drive the turbine 8, but this compressed air is not used for the bearing portion. That is, the shaft member 2 is rotated by the turbine 8, and the bearing surface 1a and the shaft surface are generated by the pressure generated in the air by the dynamic pressure generating groove 19 provided in the shaft surface by the relative movement between the bearing surface 1a and the shaft surface 2a. Separate 2a. When oil is used as the fluid, measures to prevent oil leakage shall be taken separately. At this time, compressed air can be used to drive the turbine 8 and oil can be used as a bearing fluid. Since compressed air is not used for the bearing, high rotation can be obtained even at low pressure.

  When the hydrodynamic bearing of the present invention of each embodiment is used, the housing 10 or the shaft hole member 1 is further housed in an exterior cylinder, and a collet chuck or the like for fixing a tool such as a grindstone or a blade is provided on the tip side. It is better to fix the pipes. In each embodiment, exhaust is performed to the front end side and the rear end side. However, depending on the target, a discharge path is appropriately provided so that exhaust is not performed.

DESCRIPTION OF SYMBOLS 1 Shaft hole member 1a Slope, bearing surface 2 Shaft member 2a Shaft surface 3 Shaft 4 1st flange 5 2nd flange 6 Nozzle 7 Outlet 8 Turbine 9 Lock nut 10 Housing 11 Outer ring 12 Inner ring 13 End part inner ring 14 Fixing flange 15 inner ring collar 16 outer ring collar 17 fixing ring 18 sub nozzle 19 dynamic pressure generating groove 20 dynamic pressure generating inner ring 21 inner ring for dynamic pressure generating end 22 collar 23 turbine exhaust port 24 collet chuck 25 grindstone 26 sub nozzle piping 27 Nozzle piping

Claims (8)

A shaft hole member having a bearing surface of a predetermined width in the axial direction on the inner peripheral surface defining the shaft hole;
A shaft member rotatably held in the shaft hole and having a shaft surface facing the bearing surface;
Fluid supply means for supplying fluid between the bearing surface and the shaft surface;
A hydrodynamic bearing device comprising:
Both the bearing surface and the shaft surface are frustoconical side surfaces, and the fluid supply means supplies fluid in the axial direction between the bearing surface and the shaft surface. Fluid bearing device. The shaft hole member has at least one set of the bearing surfaces in a set of two in which the apex directions of the cones are opposite to each other.
2. The hydrodynamic bearing device according to claim 1, wherein the shaft member has at least one set of the shaft surfaces respectively opposed to the one set of the preceding bearing surfaces.   The hydrodynamic bearing device according to claim 1, wherein the fluid is a gas.   The hydrodynamic bearing device according to claim 3, wherein the gas is air.   5. The hydrodynamic bearing device according to claim 1, wherein the bearing surface and the shaft surface facing the shaft surface have the same angle with respect to the axial direction of the shaft member on an axial cross section.   The hydrodynamic bearing device according to claim 1, wherein a minimum inner diameter of the bearing surface is smaller than a maximum outer diameter of the shaft surface.   The hydrodynamic bearing device according to claim 1, wherein there are at least four of the bearing surface and the shaft surface in the axial direction. A shaft hole member having a bearing surface of a predetermined width in the axial direction on the inner peripheral surface defining the shaft hole;
A shaft member rotatably held in the shaft hole and having a shaft surface facing the bearing surface;
Fluid supply means for supplying fluid between the bearing surface and the shaft surface;
The bearing surface and the shaft surface are both frustoconical side surfaces, and the fluid supply means supplies a fluid in the axial direction between the bearing surface and the shaft surface;
A drive unit having a turbine driven by a fluid coaxially formed in the shaft member and a nozzle port for ejecting fluid toward the turbine formed in the shaft hole member;
A rotary drive device comprising:

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