JP6804231B2 - Air turbine drive spindle - Google Patents

Description

The present invention relates to an air turbine drive spindle applied to precision processing machines, electrostatic coating devices and the like.

Conventionally, an air turbine drive spindle used in a precision processing machine or an electrostatic coating device is known. For example, Japanese Patent Application Laid-Open No. 9-72338 discloses an air turbine drive spindle in which a sleeve that rotatably supports a rotating shaft is held in a housing. In JP-A-9-72338, the sleeve is supported by an O-ring with respect to the housing. Such an O-ring is usually made of an elastic body such as rubber. The O-ring has a function of absorbing vibration generated by high-speed rotation of the rotating shaft of the air turbine drive spindle and stabilizing the operation of the air turbine drive spindle.

Japanese Unexamined Patent Publication No. 9-72338

Here, since the electrostatic coating device or the like in which the air turbine drive spindle is used is used in a solvent atmosphere, it is necessary to use a material having excellent solvent resistance for the above-mentioned O-ring. As such a material having excellent solvent resistance, a perfluoroelastomer is known. The perfluoroelastomer has excellent solvent resistance, but has a higher hardness than the rubber material generally used for O-rings. As a result, the perfluoroelastomer O-ring has a smaller amount of deformation with respect to an external force than a general O-ring. Therefore, the vibration caused by the rotation of the rotating shaft cannot be sufficiently absorbed by the O-ring, and as a result, the rotating shaft of the spindle may not be stably rotated at high speed.

Further, the material of the O-ring may be appropriately selected according to the usage environment of the spindle, not limited to the perfluoroelastomer as described above. In such a case, from the viewpoint of increasing the degree of freedom in selecting the material, even when an O-ring made of a material having a higher hardness than a general O-ring material is used, the vibration due to the rotation of the rotating shaft can be sufficiently absorbed. , There is a demand for an air turbine drive spindle capable of stably rotating the rotating shaft at high speed.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an air turbine drive spindle capable of stably rotating a rotating shaft at a high speed.

The air turbine drive spindle according to the present invention includes a rotating shaft having an outer peripheral surface, an inner cover member that surrounds at least a part of the outer peripheral surface of the rotating shaft, and an outer cover member that surrounds at least a part of the outer peripheral surface of the inner cover member. The outer cover member is formed with a communication hole portion connected to a gap formed between the inner cover member and the outer cover member, and faces the outer peripheral surface of the inner cover member and the inner cover member of the outer cover member. A first groove and a second groove arranged so as to sandwich the communication hole portion are formed on one of the inner peripheral surfaces in the direction along the central axis of the rotation axis, and the gap is the first. The outer peripheral surface of the inner cover member, which has elasticity and is engaged with the first groove and the supply part which communicates with each of the groove and the second groove and supplies gas to the gap through the communication hole part. And the first O-ring in contact with any one of the inner peripheral surfaces of the outer cover member facing the inner cover member, and the second groove, which has elasticity and is of the inner cover member. The outer peripheral surface and the inner peripheral surface of the outer cover member are further provided with a second O-ring in contact with the other, and the first groove and the second groove are respectively a first side wall and a second side wall. It has a side wall and a bottom connecting the first side wall and the second side wall, and in each of the first groove and the second groove, the distance from the first side wall to the communication hole is determined by the second side wall. The distance from the bottom to the top of the first side wall in each of the first groove and the second groove is longer than the distance from the bottom to the top of the second side wall. It's short .

According to the present invention, the rotating shaft can be stably rotated at high speed.

It is sectional drawing of the cross-section of the air turbine drive spindle which concerns on Embodiment 1. FIG. It is sectional drawing which shows the 1st groove part and 2nd groove part of Embodiment 1. FIG. It is sectional drawing which shows the 2nd groove part of Embodiment 1. FIG. It is sectional drawing which shows the 1st groove part and the 2nd groove part of the reference example when the gas is not supplied from the supply part. It is sectional drawing which shows the 2nd groove part of the reference example when the gas is not supplied from the supply part. It is sectional drawing which shows the 1st groove part and the 2nd groove part of the reference example when a gas is supplied from a supply part. It is sectional drawing which shows the 2nd groove part of the reference example when a gas is supplied from a supply part. It is sectional drawing which shows the 1st groove part and the 2nd groove part of the 1st modification. It is sectional drawing which shows the 2nd groove part of the 1st modification. It is sectional drawing which shows the 1st groove part and the 2nd groove part of the 2nd modification. It is sectional drawing which shows the 2nd groove part of the 2nd modification. It is sectional drawing which shows the 1st groove part and the 2nd groove part of the 3rd modification. It is sectional drawing which shows the 2nd groove part of the 3rd modification. It is a partial cross-sectional schematic diagram of the air turbine drive spindle which concerns on Embodiment 2. FIG. It is sectional drawing which shows the 1st groove part and 2nd groove part of Embodiment 2. It is sectional drawing of the cross-section of the air turbine drive spindle which concerns on Embodiment 3. FIG. It is sectional drawing which shows the 2nd groove part of Embodiment 3. FIG. It is a partial cross-sectional schematic diagram of the air turbine drive spindle which concerns on Embodiment 4. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings below, the same or corresponding parts are given the same reference numbers, and the explanations are not repeated.

(Embodiment 1)
<Structure of Air Turbine Drive Spindle 200>
The air turbine drive spindle 200 according to the first embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view for explaining the air turbine drive spindle 200.

The air turbine drive spindle 200 includes a rotating shaft 1, a journal bearing 7 that supports the rotating shaft 1 in the radial direction, a thrust bearing 8 that supports the rotating shaft 1 in the thrust direction, and a journal bearing 7 and a thrust bearing that support the rotating shaft 1. A first O-ring 23 arranged between the housing assembly 2 rotatably supported via the eighth, the outer cover member 5 located on the outer peripheral side of the housing assembly 2, and the outer cover member 5 and the housing assembly 2. And a second O-ring 24 and the like.

A nozzle plate 6 is fixedly provided on the outer cover member 5 so as to cover the rotation shaft 1 in the thrust direction. The outer cover member 5 surrounds at least a part of the outer peripheral surface 3a of the inner cover member 3. The nozzle plate 6 is provided with a driving gas supply unit. The journal bearing 7 and the thrust bearing 8 are configured as, for example, a hydrostatic gas bearing.

The rotating shaft 1 includes a shaft portion 1b having a cylindrical shape and a thrust plate portion 1c formed so as to extend in the radial direction with respect to the shaft portion 1b. The thrust plate portion 1c is coupled to one end of the shaft portion 1b in the thrust direction. Hereinafter, the side in which the thrust plate portion 1c is provided in the thrust direction is referred to as a rear side, and the side opposite to the rear side in the thrust direction of the shaft portion 1b is referred to as a front side. A through hole 17 extending in the thrust direction is formed in the shaft portion 1b and the thrust plate portion 1c. When the spindle is configured for an electrostatic coating machine, a conical cup 37 is attached to the front end of the rotating shaft 1 as shown in FIG. A paint supply pipe 45 for supplying paint to the cup 37 is arranged inside the through hole 17. The thrust plate portion 1c is formed with a rotary blade 15 and a rotated detection portion (not shown) arranged on the inner peripheral side of the rotary blade 15.

A part of the shaft portion 1b of the rotating shaft 1 is housed in the housing assembly 2. The housing assembly 2 includes an inner cover member 3 and a bearing sleeve 4. The bearing sleeve 4 faces each part of the outer peripheral surface 1a of the shaft portion 1b of the rotating shaft 1 and the front plane of the thrust plate portion 1c, and is formed so as to surround a part of the shaft portion 1b. The inner cover member 3 is arranged on the outer peripheral side of the bearing sleeve 4 in the radial direction and is fixed to the bearing sleeve 4. The inner cover member 3 surrounds at least a part of the outer peripheral surface 1a of the shaft portion 1b from the outer peripheral side of the bearing sleeve 4.

A first groove 33 and a second groove 34 are formed on the outer peripheral surface 3a of the inner cover member 3. The first groove 33 and the second groove 34 are annular grooves formed on the outer peripheral surface 3a of the inner cover member 3 so as to orbit around the rotation center axis of the rotation shaft 1. The first O-ring 23 is engaged with the first groove 33. The second O-ring 24 is engaged with the second groove 34. The first O-ring 23 is located on the rear end side of the center of the bearing sleeve 4 in the thrust direction of the rotating shaft 1. The second O-ring 24 is located on the front end side of the center of the bearing sleeve 4 in the thrust direction of the rotating shaft 1. The first O-ring 23 and the second O-ring 24 come into contact with the inner peripheral surface 5a of the outer cover member 5. As a result, the first O-ring 23 and the second O-ring 24 hold the bearing unit (rotating shaft 1, housing assembly 2, etc.) against the outer cover member 5. The structure is such that the inner cover member 3 and the outer cover member 5 do not come into direct contact with each other by the first O-ring 23 and the second O-ring 24.

Both the first O-ring 23 and the second O-ring 24 are elastic members. Further, as the material of the first O-ring 23 and the second O-ring 24, for example, it is preferable to use a material having high resistance to a solvent. For example, a perfluoroelastomer can be used as the material. Further, the material may be another material such as fluororubber or nitrile rubber.

As shown in FIG. 1, the thrust plate portion 1c of the rotating shaft 1 has a region (thick portion) located on the rotation center axis side (center side) in the radial direction and outward in the radial direction from the thick portion. It is located and has a thin portion that is thin in the thrust direction. The thick portion is formed so as to surround the through hole 17. The thin-walled portion is formed so as to surround the thick-walled portion.

The rotary blade 15 is formed so as to extend in the thrust direction from the surface located on the rear side on the thin-walled portion of the thrust plate portion 1c. The rotary shaft 1 is provided so that the rotary blade 15 can rotate by receiving the gas ejected from the driving gas supply unit (not shown). The plurality of rotary blades 15 are provided so as to be spaced apart from each other in the rotation direction of the rotation shaft 1. Preferably, in the plurality of rotary blades 15, adjacent rotary blades 15 are provided at equal intervals. The plurality of rotary blades 15 are arranged along the outer circumference of the thrust plate portion 1c. The cross-sectional shape of the plurality of rotary blades 15 perpendicular to the thrust direction may be any shape. For example, the cross-sectional shape is a front curved surface portion located forward in the rotation direction and formed convex in the rotation direction, and a rear curved surface portion located rearward in the rotation direction and formed convex in the rotation direction. It has a part.

A rotation-detected portion (not shown) is formed on the rear surface of the thick portion of the thrust plate portion 1c. The rotation detection unit can adopt an arbitrary configuration for optically detecting the rotation of the rotation shaft 1, but for example, surface treatment is applied so that the reflectance is different for each of a plurality of regions divided in the rotation direction. It may have been. Specifically, of the surfaces located on the rear side of the thick portion, when half of the area of the rotation axis 1 in the rotation direction is irradiated with light such as laser light, the reflected light is more than the other half. It is provided so that the strength is high.

The supply unit (air compressor) 100 supplies (spouts) bearing gas from the bearing gas supply port 9. A bearing gas supply path 10 is formed in the outer cover member 5, the inner cover member 3, and the bearing sleeve 4. Further, a gap 43 is formed between the outer cover member 5 and the inner cover member 3. The bearing gas supply path 10 and the gap 43 communicate with each other through the communication hole portion 25. Gas is supplied from the supply unit 100 to the bearing gas supply path 10 and the gap 43. The bearing gas supply path 10 supplies gas to the journal bearing 7 and the thrust bearing 8 inside the bearing sleeve 4 and the portion provided along the radial direction of the rotating shaft 1, so that the thrust direction and the radial of the rotating shaft 1 are supplied. Includes a portion provided along the direction. The gap 43 is provided in a direction parallel to the thrust direction of the rotation shaft 1. Further, the first groove 33 and the second groove 34 are arranged so as to sandwich the communication hole portion 25 in the thrust direction.

A bearing gap 41 is provided between the shaft portion 1b and the bearing sleeve 4. A bearing gap 42 is also provided between the thrust plate portion 1c and the bearing sleeve 4. One end of the bearing gas supply path 10 communicates with the bearing gas supply port 9 on the outer peripheral surface of the outer cover member 5, and the other end communicates with the bearing gap 41 and the bearing gap 42. In the bearing gas supply path 10, the hole diameter of the portion communicating with the bearing gap 41 and the bearing gap 42 is smaller than the hole diameter of the bearing gas supply port 9, so that a so-called throttle is formed. When the gas is supplied from the supply unit 100, the bearing gas supply path 10, the gap 43, the bearing gap 41, and the bearing gap 42 can be filled with the bearing gas. The bearing gas supplied to the bearing gas supply path 10 is supplied to the gap 43 through the communication hole 25. The bearing gas is, for example, compressed air.

The journal bearing 7 is configured by supplying the gas supplied from the supply unit 100 to the bearing gas supply path 10 to the bearing gap 41. The thrust bearing 8 is composed of a pressing force and an attractive force of the magnet 16 due to the gas supplied from the supply unit 100 to the bearing gas supply path 10 being supplied to the bearing gap 42.

On the inner cover member 3, a magnet 16 is arranged in a region facing the thrust plate portion 1c in the thrust direction. The magnet 16 applies a magnetic force to the thrust plate portion 1c. The magnet 16 is, for example, a permanent magnet. The magnet 16 attracts the thrust plate portion 1c by magnetic force. The magnet 16 is provided so as to face, for example, the thin portion of the thrust plate portion 1c on which the rotary blade 15 is formed in the thrust direction. The plane shape of the magnet 16 when viewed from the thrust direction is, for example, an annular shape.

The outer cover member 5 is fixed to the nozzle plate 6 in the thrust direction. The nozzle plate 6 surrounds a portion of the rotating shaft 1 that is not housed in the housing assembly 2 and the outer cover member 5 (the outer peripheral end surface of the thrust plate portion 1c in the radial direction and the surface located behind the thrust plate portion 1c). Is formed in.

The nozzle plate 6 is arranged on the rear side of the rotation shaft 1. A drive air supply path 13 and a drive air supply nozzle 14 are formed inside the nozzle plate 6. The drive air supply passage 13 and the drive air supply nozzle 14 are flow passages for supplying the drive gas to the rotary blade 15. The driving gas is, for example, compressed air. The drive gas supply unit that supplies the drive gas from the drive gas air supply port 12 may also be used as the supply unit 100, or may be different from the supply unit 100.

The drive air supply nozzle 14 is provided on the rotary blade 15 so as to be able to eject the drive gas from the outside to the inside of the rotary shaft 1 in the radial direction. A plurality of drive air supply passages 13 and drive air supply nozzles 14 may be formed at intervals in the rotation direction. That is, the drive air supply passage 13 and the drive air supply nozzle 14 can simultaneously supply the drive gas in the same rotation direction to the rotary blades 15 provided at arbitrary intervals in the rotation direction. It may be provided.

The nozzle plate 6 is formed with a rotation sensor insertion port 18 on the outer peripheral side in the radial direction with respect to the through hole 17. The rotation sensor insertion port 18 is formed so as to face the rotated detection unit installed in the thrust plate portion 1c in the thrust direction. The rotation sensor insertion port 18 is formed to irradiate the rotation detection unit with light such as a laser beam and arrange a rotation sensor for obtaining reflected light. By providing such a configuration, the air turbine drive spindle 200 can optically measure the rotation speed of the rotating shaft 1.

The exhaust hole 11 is formed in the nozzle plate 6 on the central side in the radial direction with respect to the drive air supply passage 13 and the drive air supply nozzle 14. The exhaust hole 11 is formed so as to communicate with the outside of the nozzle plate 6 from the exhaust space 20.

Next, the first groove 33 and the second groove 34 will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view for explaining the first groove 33 and the second groove 34. FIG. 2 is an enlarged view of the first groove 33 and the second groove 34. As shown in FIG. 2, the first groove 33 and the second groove 34 communicate with the gap 43.

As shown in FIG. 2, the elastic first O-ring 23 and the elastic second O-ring 24 are in contact with the inner peripheral surface 5a of the outer cover member 5. The inner peripheral surface 5a faces the inner cover member 3. By operating the air turbine drive spindle 200, when a cup 37 or the like is mounted on the tip end side of the rotating shaft 1 and rotates, vibration is generated due to the swinging on the tip end side. The vibration is generated once by one rotation of the rotating shaft 1. Even when the vibration is generated, the first O-ring 23 and the second O-ring 24 can absorb the vibration by deforming the first O-ring 23 and the second O-ring 24. As described above, the first O-ring 23 and the second O-ring 24 have damping performance.

Both the first O-ring 23 and the second O-ring 24 are installed so as to be pressed against the inner peripheral surface 5a of the outer cover member 5 and deformed. As a result, the bearing gas supplied from the supply unit 100 can be sealed in the gap 43, so that the bearing gas can be prevented from leaking to the outside from the gap 43. Further, both the first O-ring 23 and the second O-ring 24 also have a sealing performance because they prevent the bearing gas from leaking to the outside.

Next, the second O-ring 24 and the second groove 34 will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view for explaining the second O-ring 24 and the second groove 34, and is an enlarged view of the locations of the second O-ring 24 and the second groove 34 in FIG. .. The second groove 34 includes a first side wall 34a, a second side wall 34b, a bottom 34c (bottom surface), a chamfered portion 34d and a top 34e. As shown in FIG. 2, the distance L1 from the communication hole portion 25 to the first side wall 34a is longer than the distance L2 from the communication hole portion 25 to the second side wall. In other words, when the gas is supplied by the supply unit 100, the side wall on the downstream side of the gas flow (see arrow α in FIG. 3) becomes the first side wall 34a, which is on the upstream side of the gas flow. The side wall becomes the second side wall 34b.

The height H5 from the bottom 34c to the upper end (top 34e) of the first side wall 34a is lower than the height H4 from the bottom 34c to the upper end of the second side wall 34b. As described above, in order to make the height H5 lower than the height H4, in this embodiment, the chamfered portion 34d connected to the upper end of the first side wall 34a is formed. In the example of FIG. 3, the chamfered portion 34d is a tapered surface. The space A is formed by forming the tapered surface.

The distance H2 in FIG. 3 indicates a range (distance) in which the second O-ring 122 is not in contact with another component (inner cover member 3) in the radial direction. In other words, the distance H2 is also the distance from the portion of the first side wall 34a closest to the inner peripheral surface 5a of the outer cover member 5 (that is, the top 34e) to the inner peripheral surface 5a of the outer cover member 5. The distance H3 indicates the distance from the bottom portion 34c to the inner peripheral surface 5a of the outer cover member 5. As shown in FIG. 2, the first groove 33 also has the same structure as the second groove 34.

<Operation of air turbine drive spindle 200>
Next, the operation of the air turbine drive spindle 200 according to the present embodiment will be described.

When the air turbine drive spindle 200 operates, the drive gas supply unit supplies the drive gas. The drive gas supplied from the drive gas supply unit is supplied to the drive air supply nozzle 14 from the drive gas air supply port 12 through the drive air supply path 13. The driving gas supplied to the driving air supply nozzle 14 is directed toward the rotary blade 15 of the thrust plate portion 1c of the rotating shaft 1 along a direction substantially parallel to the tangential direction (rotation direction) of the thrust plate portion 1c. It is spouted. The rotary blade 15 receives the ejected driving gas at the rear curved surface portion. At this time, the driving gas ejected to the rotary blade 15 reaches the outer peripheral side of the rear curved surface portion, is changed in direction by flowing along the rear curved surface portion, and is external from the exhaust hole 11 via the exhaust space 20. Is exhausted to. The reaction force of the force applied to the driving gas acts on the rotary blade 15, and the thrust plate portion 1c of the rotary shaft 1 is given a rotational torque. As a result, the rotation shaft 1 rotates along the rotation direction. The rotation speed of the rotating shaft 1 can be, for example, tens of thousands of rpm or more. That is, the above-mentioned air turbine drive spindle 200 is suitable for, for example, a spindle for an electrostatic coating machine.

When the air turbine drive spindle 200 operates, the supply unit 100 supplies the bearing gas from the bearing gas supply port 9. The bearing gas is supplied to the gap 43 in the direction of arrow α (see FIG. 3) via the bearing gas supply path 10 and the communication hole portion 25. When the bearing gas is supplied to the gap 43, as shown in FIGS. 2 and 3, the second O-ring 24 has a lower pressure side (communication hole portion 25) due to the influence of the bearing gas (compressed air). It is pushed away from). When the second O-ring 24 is pushed out to the side where the pressure is low, the second O-ring 24 is deformed by being pressed (pressed) against the first side wall 34a. Then, a part 24a of the second O-ring 24 moves to the space A in a state where the surface of the part 24a is not restrained and has an elastic force.

That is, even when the second O-ring 24 is pressed against the first side wall 34a, the height H5 of the first side wall 34a is relatively lower than the height H4, so that the surface surface is The volume of the part 24a that is not constrained and can be deformed relatively freely can be sufficiently increased. Therefore, even if the bearing gas is supplied to the gap 43, the elastic stroke of the second O-ring 24 is ensured by the presence of a part 24a, so that the damping performance of the second O-ring 24 is ensured.

<Effect>
A reference example of the air turbine drive spindle will be described with reference to FIGS. 4 to 7. 4 to 7 are schematic cross-sectional views for explaining the first groove 131, the second groove 132, and the like of the reference example of the air turbine drive spindle. The first O-ring 121 is engaged with the first groove 131 and the second O-ring 122 is engaged with the second groove 132. The configuration of the air turbine drive spindle according to the reference example is the same as that of the air turbine drive spindle 200 described with reference to FIG. 1, except for the cross-sectional shapes of the first groove 131 and the second groove 132.

FIG. 4 shows a state in which the bearing gas is not supplied from the supply unit 100 to the gap 43, and FIG. 5 shows an enlarged view of the second O-ring 122 and the like. FIG. 6 shows a state in which the bearing gas is supplied from the supply unit 100 to the gap 43, and FIG. 7 shows an enlarged view of the second O-ring 122 and the like. The distance H1 in FIGS. 5 and 7 is a radial direction within a range in which the outer cover member 5 and the inner cover member 3 in the second O-ring 122 are not in contact with other parts (inner cover member 3). Indicates the length. This range is a range having the elastic force of the second O-ring 122 because the surface is not constrained by other parts and can be deformed relatively freely.

As shown in FIG. 5, the heights of the side walls 132a and 132b of both side walls 132 of the second groove 132 in which the second O-ring 122 is engaged are the same. Therefore, when the bearing gas is supplied from the supply unit 100 to the gap 43, the amount of decrease in the distance H1 is large as shown in FIGS. 5 and 7 as compared with the air turbine drive spindle 200 according to the present embodiment. .. The amount of decrease in the distance H1 is the value of the distance H1 when the bearing gas is supplied to the gap 43 from the “value of the distance H1 when the bearing gas is not supplied to the gap 43 (see FIG. 5)”. (See FIG. 7) ”is subtracted. As described above, since the amount of decrease in the distance H1 is large, the distance H1 when the bearing gas shown in FIG. 7 is supplied is small, so that the elastic stroke of the second O-ring 122 is small. Therefore, in the air turbine drive spindle of the reference example, when the bearing gas is supplied from the supply unit 100, the damping performance of the air turbine drive spindle is deteriorated as compared with the case where the bearing gas is not supplied.

On the other hand, in the air turbine drive spindle 200 of the present embodiment, as shown in FIG. 3, the height H5 of the first side wall 34a is lower than the height H4 of the second side wall 34b. Therefore, when the bearing gas is supplied from the supply unit 100 to the gap 43, as shown in FIG. 3, a part constituting the elastic stroke of the second O-ring 24 as compared with the air turbine drive spindle of the reference example. The distance H2 corresponding to the size of 24a can be set to be larger than the distance H1 (see FIG. 7). That is, the amount of decrease in the distance H2 can be reduced. Here, the amount of decrease in the distance H2 is the difference between the "distance H2 when the bearing gas is not supplied to the gap 43" and the "distance H2 when the bearing gas is supplied to the gap 43". As a result, the amount of reduction in the elastic stroke of the second O-ring 24 can be reduced, so that deterioration of the damping performance of the air turbine drive spindle can be suppressed when the bearing gas is supplied.

<First modification>
Next, with reference to FIGS. 8 and 9, the first groove 331 and the second groove 341 which are the first modifications of the first groove 33 and the second groove 34 shown in FIG. 1 are formed. explain. FIG. 8 is a schematic cross-sectional view for explaining the first groove 331 and the second groove 341. FIG. 9 shows an enlarged view of the second groove 341. The second groove 341 includes a first side wall 341a, a second side wall 341b, a bottom 341c (bottom surface), a notch 341d, and a top 341e.

The air turbine drive spindle according to the first modification of the present embodiment having the first groove 331 and the second groove 341 shown in FIGS. 8 and 9 has a configuration other than the above with respect to FIGS. 1 to 3. It is the same as the air turbine drive spindle shown in.

The difference between the second groove 341 shown in FIGS. 8 and 9 and the second groove 34 shown in FIGS. 1 to 3 is that the second groove 34 includes the chamfered portion 34d. The second groove 341 is a point including a notch (step portion) 341d. As described above, the second groove 341 includes a notch 341d connected to the upper end of the first side wall 341a. By forming the notch portion 341d, the height H5 of the first side wall 341a becomes lower than the height H4 of the second side wall 341b. Further, the top portion 341e is formed by forming the notch portion 341d. The distance from the top portion 341e to the inner peripheral surface 5a of the outer cover member 5 is defined as the distance H2. Even with such a configuration, when the bearing gas is supplied to the gap 43, a part 24a of the second O-ring 24 moves in a state of having elastic force without restraining the surface of the part 24a. Space B can be formed. Therefore, the air turbine drive spindle shown in FIGS. 8 and 9 has the same effect as the air turbine drive spindle according to the present embodiment shown in FIGS. 1 to 3.

<Second modification>
Next, with reference to FIGS. 10 and 11, the first groove 332 and the second groove 342 which are the second modification of the first groove 33 and the second groove 34 will be described. FIG. 10 is a schematic cross-sectional view for explaining the first groove 332 and the second groove 342. FIG. 11 shows an enlarged view of the second groove 342. The second groove 342 includes a first side wall 342a, a second side wall 342b, a bottom 342c (bottom surface), and a top 342e.

The air turbine drive spindle according to the second modification of the present embodiment having the first groove 332 and the second groove 342 shown in FIGS. 10 and 11 has a configuration other than the above with respect to FIGS. 1 to 3. It is the same as the air turbine drive spindle shown in.

The first groove 332 and the second groove 342 of the second modification have the following structure. In the following, among the outer peripheral surfaces of the inner cover member 3, the region near the first side wall 342a is referred to as the first region 3b, and the region near the second side wall 342b is referred to as the second region 3c. In the second modification, the shortest distance P1 in the radial direction between the first region 3b and the bottom portion 342c is shorter than the shortest distance P2 in the radial direction between the second region 3c and the bottom portion 342c. Further, P1 = H5 and P2 = H4. Further, the distance from the top portion 342e to the inner peripheral surface 5a of the outer cover member 5 is defined as the distance H2. The height H5 of the first side wall 341a is lower than the height H4 of the second side wall 341b. Even with such a configuration, when the bearing gas is supplied to the gap 43, a part 24a of the second O-ring 24 moves in a state where the surface of the part 24a is not restrained and has an elastic force. Space C can be formed. Therefore, the air turbine drive spindle shown in FIGS. 10 and 11 has the same effect as the air turbine drive spindle according to the present embodiment shown in FIGS. 1 to 3.

<Third variant>
Next, the first groove 333 and the second groove 343, which are third modifications of the first groove 33 and the second groove 34, will be described with reference to FIGS. 12 and 13. FIG. 12 is a schematic cross-sectional view for explaining the first groove 333 and the second groove 343. FIG. 13 shows an enlarged view of the second groove 343. The second groove 343 includes a first side wall 343a, a second side wall 343b, a bottom 343c (bottom surface), a chamfered portion 343d, and a top 343e.

The air turbine drive spindle according to the second modification of the present embodiment having the first groove 333 and the second groove 343 shown in FIGS. 12 and 13 is shown in FIGS. 1 to 1 for configurations other than the above. This is the same as the air turbine drive spindle shown in 3.

The chamfered portion 34d of the present embodiment shown in FIG. 3 is assumed to be a tapered surface (flat surface), but the chamfered portion 343d of the third modification has a curved surface shape as shown in FIG. .. As shown in FIG. 13, the chamfered portion 343d preferably has a shape bulging outward. By forming the chamfered portion 343d, the top portion 343e is formed. The distance from the top portion 343e to the inner peripheral surface 5a of the outer cover member 5 is defined as the distance H2. Even with such a configuration, when the bearing gas is supplied to the gap 43, a part 24a of the second O-ring 24 moves in a state where the surface of the part 24a is not restrained and has an elastic force. Space D can be formed. Therefore, the air turbine drive spindle shown in FIGS. 12 and 13 has the same effect as the air turbine drive spindle according to the present embodiment shown in FIGS. 1 to 3. As a further modification of the chamfered portion 343d, the chamfered portion 343d may have a shape dented in one direction of the rotation axis.

<About the range of distance H2>
Next, a preferable range of the distance H2 described in the present embodiment and the first to third modifications will be described. When the air turbine drive spindle 200 is of a size used for, for example, an electrostatic coating machine, the distance H2 preferably satisfies the condition of 0.5 mm ≦ H2 ≦ (H3) / 2. By setting the value of the distance H2 to a value within such a range, the air turbine drive spindle 200 can be operated stably.

Further, the height H5 of the first side wall 34a may be equal to or larger than the radius of the cross section of the second O-ring 24. As a result, when the bearing gas is supplied from the supply unit 100, deterioration of the damping performance of the air turbine drive spindle can be suppressed, and the second O-ring 24 does not deviate from the second groove 34. Can be done.

(Embodiment 2)
<Structure of air turbine drive spindle>
Next, the air turbine drive spindle 300 according to the second embodiment will be described with reference to FIGS. 14 and 15. FIG. 14 is a schematic cross-sectional view for explaining the air turbine drive spindle 300, and shows the upper half of the air turbine drive spindle 300.

In the first embodiment, two O-rings (the first O-ring 23 and the second O-ring 24) are used, but in the second embodiment, in addition to the two O-rings, two more are used. Use a book O-ring.

In the second embodiment, a third groove 133 and a fourth groove 134 are formed on the outer peripheral surface 3a of the inner cover member 3 in addition to the first groove 33 and the second groove 34. The third groove 133 and the fourth groove 134 are formed so as to sandwich the first groove 33 and the second groove 34 in the thrust direction. The third groove 133 and the fourth groove 134 are annular grooves formed on the outer peripheral surface 3a of the inner cover member 3 so as to orbit around the rotation center axis of the rotation shaft 1. A third O-ring 123 is engaged with the third groove 133. A fourth O-ring 124 is engaged with the fourth groove 134.

The air turbine drive spindle according to the second embodiment shown in FIGS. 14 and 15 is the same as the air turbine drive spindle shown in FIGS. 1 to 3 except for the above configuration.

The first O-ring 23 and the second O-ring 24 of the first embodiment have damping performance and sealing performance. In the second embodiment, the first O-ring 23 and the second O-ring 24 are provided with sealing performance and damping performance, while the third O-ring 123 and the fourth O-ring 124 are provided with sealing performance. Instead, it has damping performance as its main characteristic.

As the shape of the first groove 33 and the second groove 34, any one of the shapes described in the present embodiment and the first to third modifications is adopted. Thereby, the sealing performance and the damping performance of the first O-ring 23 and the second O-ring 24 can be guaranteed. Further, for the third groove 133 and the fourth groove 134, any of the shapes described in the present embodiment and the first to third modified examples may be adopted, which will be described in the reference example. It may have a shaped shape. The shape described in the reference example is a shape in which the heights of both side walls of the groove are the same.

Since the first O-ring 23 and the second O-ring 24 have sealing performance, even if the supply unit 100 supplies gas to the gap 43, the third groove 133 and the fourth groove 134 can be reached. This gas is not supplied (not reachable). Therefore, the third O-ring 123 and the fourth O-ring 124 are not pressed by the gas and pressed against the side wall of the groove. Therefore, the damping performance of the third O-ring 123 and the fourth O-ring 124 is not deteriorated.

When the rotating shaft 1 rotates, the first O-ring 23 and the second O-ring 24 are installed near the center of gravity 29 of the rotating shaft 1, so that the first O-ring 23 and the second O-ring 24 are moved. Vibration can occur due to the centered rubbing motion. Further, the third O-ring 123 is installed behind the air turbine drive spindle 300, and the fourth O-ring 124 is installed in front of the air turbine drive spindle 300. Therefore, the kinetic energy of this precession increases at the location where the third O-ring 123 and the fourth O-ring 124 are installed. As described above, even if the supply unit 100 supplies the gas, the damping performance of the third O-ring 123 and the fourth O-ring 124 does not deteriorate. Therefore, the vibration due to this precession is applied to the third O-ring. It can be sufficiently absorbed by the 123 and the fourth O-ring 124.

In this way, by dividing the roles of the first O-ring 23 and the second O-ring 24, and the third O-ring 123 and the fourth O-ring 124, the respective performances can be fully exhibited. it can.

(Embodiment 3)
<Structure of air turbine drive spindle>
Next, the air turbine drive spindle 500 according to the third embodiment will be described with reference to FIG. FIG. 16 is a schematic cross-sectional view for explaining the air turbine drive spindle 500.

In the first embodiment (see FIG. 1), the inner cover member 3 is formed with a first groove 33 and a second groove 34. In the third embodiment, the first groove 533 and the second groove 534 are formed on the inner peripheral surface 505a of the outer cover member 505, and the groove is not formed on the inner cover member 503.

FIG. 17 is a schematic cross-sectional view for explaining the first groove 533 and the second groove 534. FIG. 17 is an enlarged view of the first groove 533 and the second groove 534.

The first O-ring 23 is engaged with the first groove 533. The second O-ring 24 is engaged with the second groove 534. The first groove 533 and the second groove 534 communicate with the void 43. The first O-ring 23 comes into contact with the outer peripheral surface 503a of the inner cover member 503. The second O-ring 24 comes into contact with the outer peripheral surface 503a of the inner cover member 503. The shapes of the first groove 533 and the second groove 534 of FIG. 17 are the same as the shapes of the first groove 33 and the second groove 34 shown in FIGS. 2 and 3.

Further, as the shape of the first groove 533 and the second groove 534, any one of the groove shapes described in the first to third modification may be adopted. The air turbine drive spindle 500 according to the third embodiment shown in FIGS. 16 and 17 is the same as the air turbine drive spindle 200 shown in FIGS. 1 to 3 except for the above configuration. The air turbine drive spindle 500 has the same effect as the air turbine drive spindle 200.

(Embodiment 4)
Next, the air turbine drive spindle 600 according to the fourth embodiment will be described with reference to FIG. FIG. 18 is a schematic cross-sectional view for explaining the air turbine drive spindle 600, and shows the upper half of the air turbine drive spindle 600.

In the third embodiment, two O-rings (first O-ring 23 and second O-ring 24) are used, but in the fourth embodiment, in addition to the two O-rings, two more are used. Use a book O-ring.

In the fourth embodiment, the outer cover member 605 is formed with a third groove 633 and a fourth groove 634 in addition to the first groove 533 and the second groove 534. The third groove 633 and the fourth groove 634 are formed so as to sandwich the first groove 533 and the second groove 534 in the thrust direction. The third groove 633 and the fourth groove 634 are annular grooves formed in the outer cover member 605 so as to orbit around the rotation center axis of the rotation shaft 1. A third O-ring 123 is engaged with the third groove 633. A fourth O-ring 124 is engaged with the fourth groove 634. Further, as the shape of the first groove 533 and the second groove 534, any of the shapes described in the first to third modification may be adopted. The air turbine drive spindle according to the fourth embodiment shown in FIG. 18 is the same as the air turbine drive spindle shown in FIGS. 1 to 3 except for the above configurations. The air turbine drive spindle 600 has the same effect as the air turbine drive spindle 300.

Further, in the fourth embodiment, the first groove 533 and the second groove 534 are formed on either the outer peripheral surface of the inner cover member 603 or the inner peripheral surface of the outer cover member 605, while the third groove is formed. The groove 633 and the fourth groove 634 may be formed on either the outer peripheral surface of the inner cover member 603 or the inner peripheral surface of the outer cover member 605.

<O-ring material>
The materials of the first O-ring 23 and the second O-ring 24 and the third O-ring 123 and the fourth O-ring 124 may be different from each other. As a result, the degree of freedom in selecting the material is improved. Since the third O-ring 123 and the fourth O-ring 124 are installed, the first O-ring 23 and the second O-ring 24 can be kept out of contact with the outside air as much as possible. Therefore, it is not necessary for the first O-ring 23 and the second O-ring 24 to have solvent resistance in consideration of the solvent contained in the outside air. Therefore, for the first O-ring 23 and the second O-ring 24, for example, materials having higher damping performance than the third O-ring 123 and the fourth O-ring 124 are used regardless of the solvent resistance. It is preferable to use an O-ring. The material having high damping performance is, for example, nitrile rubber or fluororubber. Since the third O-ring 123 and the fourth O-ring 124 come into contact with the outside air, they are O-rings made of a material having higher solvent resistance than the first O-ring 23 and the second O-ring 24. Is preferable.

<Crushing allowance>
Next, preferable values of the crushing allowance x3 of the third O-ring 123 and the crushing allowance x4 of the fourth O-ring 124 will be described. A cross section of the third O-ring 123 in a no-load state of the third O-ring 123, that is, in a state of not being engaged with the third groove 133 (a state in which the third O-ring 123 is not deformed). Let the diameter be d3. A cross section of the fourth O-ring 124 in a no-load state of the fourth O-ring 124, that is, in a state of not being engaged with the fourth groove 134 (a state in which the fourth O-ring 124 is not deformed). Let the diameter be d4.

Further, the distance m3 from the bottom of the third groove 133 to the inner peripheral surface 5a of the outer cover member 5 is set, and the distance m4 from the bottom of the fourth groove 134 to the inner peripheral surface 5a of the outer cover member 5 is set. When the shape of the third groove 133 is, for example, the shape of the groove shown in FIG. 3, m3 = H3. Similarly, when the shape of the fourth groove 134 is, for example, the shape of the groove shown in FIG. 3, m4 = H3.

In such a case, the crushing allowance x3 of the third O-ring 123 is expressed as, for example, x3 = d3-m3. The crushing allowance x4 of the fourth O-ring 124 is represented by, for example, x4 = d4-m4.

Regarding the crushing allowance, there are specified values specified by JIS standards, manufacturer's specifications, and the like. For example, when the diameter of the cross section of the O-ring is 2 mm, the lower limit of the specified value of the crushing allowance is specified to be 0.3 mm.

Here, since it is not essential that the third O-ring 123 and the fourth O-ring 124 have sealing performance, the crushing allowance may be smaller than the specified value. For example, the crushing allowance x3 and the crushing allowance x4 may be less than 0.3 mm.

Further, "less than 0.3 mm" means that it may be "0" or "-(minus)". That is, x3 and x4 may be 0 or “− (minus)”. The fact that x3 and x4 are 0 means that the third O-ring 123 and the fourth O-ring 124 are engaged with the third groove 133 and the fourth groove 134, respectively. It means that the O-ring 123 and the fourth O-ring 124 are just in contact with the inner peripheral surface 5a of the outer cover member 5 without being deformed. That is, when x3 and x4 are 0, it means that d3 = m3 and d4 = m4.

Further, "x3 and x4 are negative" means that when the third O-ring 123 and the fourth O-ring 124 are engaged with the third groove 133 and the fourth groove 134, respectively. , The third O-ring 123 and the fourth O-ring 124 do not come into contact with the inner peripheral surface 5a of the outer cover member 5. When x3 and x4 are negative, it means that d3 <m3 and d4 <m4. However, in the case where "x3 and x4 are negative", when the third O-ring 123 and the fourth O-ring 124 are engaged with the third groove 133 and the fourth groove 134, It is preferred that the third O-ring 123 protrudes from the third groove 133 and the fourth O-ring 124 protrudes from the fourth groove 134. If it does not protrude in this way, the outer cover member 5 and the inner cover member 3 come into contact with each other, so that the third O-ring 123 and the fourth O-ring 124 cannot have the minimum damping performance. is there.

By making the crushing allowance smaller than the specified value in this way, the third O-ring 123 and the fourth O-ring 124 are elastically deformed when the inner cover member 3 is displaced with respect to the outer cover member 5. The amount can be increased. Therefore, the third O-ring 123 and the fourth O-ring 124 can absorb the vibration caused by the rotation of the rotating shaft 1.

Further, the relational expressions for the distance m3, the distance m4, the diameter d3, and the diameter d4 may be, for example, the distance m3 may be a value larger than the value obtained by subtracting 0.3 mm from the diameter d3. Further, the distance m4 may be a value larger than the value obtained by subtracting 0.3 mm from the diameter d4.

Further, in the above description, an example in which the number of O-rings is 2 or 4 has been described. However, the number of O-rings may be 3 or more.

Although the embodiment of the present invention has been described above, it is possible to modify the above-described embodiment in various ways. Moreover, the scope of the present invention is not limited to the above-described embodiment. The scope of the present invention is indicated by the scope of claims and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

The present invention is particularly advantageously applied to an air turbine drive spindle used in electrostatic coating equipment and the like.

1 Rotating shaft, 1a, 3a outer peripheral surface, 1b shaft part, 1c thrust plate part, 2 housing assembly, 3 inner cover member, 3b first area, 3c second area, 4 bearing sleeve, 5 outer cover member, 5a inner circumference Surface, 6 Nozzle plate, 7 Journal bearing, 8 Thrust bearing, 9 Bearing gas supply port, 10 Bearing gas supply path, 11 Exhaust hole, 12 Drive gas air supply port, 13 Drive air supply path, 14 Drive air supply Nozzle, 15 thrust bearing, 16 magnet, 17 through hole, 18 thrust sensor insertion slot, 20 exhaust space.

Claims (9)

A rotating shaft with an outer peripheral surface,
An inner cover member that surrounds at least a part of the outer peripheral surface of the rotating shaft, and
An outer cover member that surrounds at least a part of the outer peripheral surface of the inner cover member is provided.
The outer cover member is formed with a communication hole portion connected to a gap formed between the inner cover member and the outer cover member.
The communication hole portion is sandwiched between the outer peripheral surface of the inner cover member and the inner peripheral surface of the outer cover member facing the inner cover member in a direction along the central axis of the rotation axis. A first groove and a second groove arranged so as to be formed,
The void communicates with each of the first groove and the second groove.
A supply unit that supplies gas to the void through the communication hole portion,
With a first O-ring that is engaged with the first groove, has elasticity, and is in contact with any one of the outer peripheral surface of the inner cover member and the inner peripheral surface of the outer cover member. ,
With a second O-ring that is engaged with the second groove, has elasticity, and is in contact with any one of the outer peripheral surface of the inner cover member and the inner peripheral surface of the outer cover member. With more
Each of the first groove and the second groove has a first side wall, a second side wall, and a bottom portion connecting the first side wall and the second side wall.
In each of the first groove and the second groove, the distance from the first side wall to the communication hole is longer than the distance from the second side wall to the communication hole.
In each of the first groove and the second groove, the distance from the bottom to the upper end of the first side wall is shorter than the distance from the bottom to the upper end of the second side wall. spindle. The air turbine drive spindle according to claim 1, wherein each of the first groove and the second groove includes a chamfered portion connected to the upper end of the first side wall. The air turbine drive spindle according to claim 1, wherein each of the first groove and the second groove includes a notch extending to the upper end of the first side wall. From the upper end of the first side wall of each of the first groove and the second groove to any one of the outer peripheral surface of the inner cover member and the inner peripheral surface of the outer cover member. The distance is
0.5 mm or more, from the bottom of each of the first groove and the second groove to any one of the outer peripheral surface of the inner cover member and the inner peripheral surface of the outer cover member. The air turbine drive spindle according to any one of claims 1 to 3, which is not more than half the distance. To either one of the pre-Symbol inner peripheral surface of the outer peripheral surface and the outer cover member of the inner cover member, in the direction along the central axis of the rotary shaft, said first groove and said second groove A third groove and a fourth groove are formed so as to sandwich the
A third O-ring that is engaged in the third groove and is in contact with any one of the outer peripheral surface of the inner cover member and the inner peripheral surface of the outer cover member.
A fourth O-ring that is engaged in the fourth groove and is in contact with any one of the outer peripheral surface of the inner cover member and the inner peripheral surface of the outer cover member. The air turbine drive spindle according to any one of 1 to 4. The air turbine drive spindle according to claim 5, wherein the material constituting the first O-ring and the second O-ring is different from the material constituting the third O-ring and the fourth O-ring. The value obtained by subtracting the distance from the bottom of the third groove to the surface of the outer cover member from the diameter of the third O-ring in the unloaded state is less than 0.3 mm.
The value obtained by subtracting the distance from the bottom of the fourth groove to the surface of the outer cover member from the diameter of the fourth O-ring in the unloaded state is less than 0.3 mm, claim 5 or 6. The air turbine drive spindle described in. Each of the first groove and the second groove is formed on the outer peripheral surface of the inner cover member.
The air turbine drive spindle according to any one of claims 1 to 7, wherein each of the first O-ring and the second O-ring comes into contact with the inner peripheral surface of the outer cover member. Each of the first groove and the second groove is formed on the inner peripheral surface of the outer cover member.
The air turbine drive spindle according to any one of claims 1 to 7, wherein each of the first O-ring and the second O-ring comes into contact with the outer peripheral surface of the inner cover member.

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