JP2007023783A - Spindle unit with air turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a structure which can improve efficiencies of rotating and stopping an impeller 2. <P>SOLUTION: A width size in the radial direction of an annular space 20b arranged between an outer peripheral surface of an impeller main body 4 and an inner peripheral surface of a housing 6b is enlarged over the whole circumference. Consequently, a turbine air nozzle or nozzles 22 and a brake air nozzle or nozzles 23 are projected from the inner peripheral surface of the housing 6b and openings (air injection holes) at the top ends of the nozzles 22, 23 are made adjacent and opposite to the outer peripheral surface of the impeller main body 4. Employing such a structure makes it possible to solve the problem. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement in a spindle device with an air turbine used to configure, for example, an electrostatic coating machine or a precision processing machine.

  4 to 5 show a first example of a conventional structure of a spindle device with an air turbine used for constituting an electrostatic spray gun of an electrostatic coating machine. In this spindle apparatus with an air turbine, an impeller 2 is fixed concentrically to the main shaft 1 at a base end portion (right end portion in FIG. 4) of a hollow main shaft 1. The impeller 2 includes an annular portion 3 and a short cylindrical impeller body 4 fixed to a radial intermediate portion of one side surface (right side surface in FIG. 4) of the annular portion 3. The annular portion 3 is coupled and fixed to the base end surface of the main shaft 1 by screwing or the like. A plurality of turbine blades 5 and 5 are formed on the outer peripheral surface of the impeller body 4 over the entire periphery.

  The main shaft 1 and the impeller 2 are rotatably supported inside the housing 6 by a radial static pressure gas bearing 7 and an axial static pressure gas bearing 8. In the illustrated example, in order to constitute the radial static pressure gas bearing 7, a radial bearing member 9 formed entirely in a cylindrical shape by a porous material is fixed inside the intermediate portion of the housing 6. The inner peripheral surface of the bearing member 9 is opposed to the outer peripheral surface of the intermediate portion of the main shaft 1 through a minute gap, and the air supply passages 10 and 10 communicating with the radial bearing member 9 are provided inside the housing 6. Further, in order to constitute the axial static pressure gas bearing 8, an axial bearing member 11 is formed on the inner side near the base end (right end in FIG. 4) of the housing 6 and is formed into a ring shape with a rectangular cross section by a porous material. While fixing, the side surface (right side surface of FIG. 4) of this axial bearing member 11 is provided with a minute gap on the outer diameter side portion of the other side surface (left side surface of FIG. 4) of the annular ring portion 3 constituting the impeller 2. Further, the air supply passages 10 and 10 are also passed through the axial bearing member 11.

  When the main shaft 1 and the impeller 2 are rotatably supported by the radial and axial static pressure gas bearings 7 and 8 as described above, the air supply passages 10 and 10 and the radial and axial bearings are supported. Compressed air is continuously supplied to the minute gaps through a large number of holes existing inside the members 9 and 11. As a result, a film of compressed air is formed in the whole of these minute gaps, so that the main shaft 1 and the impeller 2 are rotatably supported in a non-contact state with respect to the radial and axial bearing members 9 and 11. To do. The compressed air continuously supplied to the minute gaps exists in the exhaust holes 12 and 12 provided in the radial bearing member 9, the exhaust passage 13 provided in the housing 6, and the housing 6. It discharges to the external space sequentially through the gap. Although not shown, when the electrostatic spray gun is completed using the spindle device with an air turbine of this example, one side of the impeller 2 is supported by another axial static pressure gas bearing. Thus, the main shaft 1 and the impeller 2 are positioned in the axial direction.

  In addition, the inner peripheral surface of the base end portion of the housing 6 that is located radially outward of the impeller body 4 is closely opposed to the outer peripheral surface of the impeller body 4 over the entire circumference. Yes. Further, at the base end portion of the housing 6, there are a plurality of circumferential locations (six locations at regular intervals in the circumferential direction) inside the portion located radially outward of the impeller body 4. The turbine air nozzle holes 14 and 14 are formed. The central axes of the turbine air nozzle holes 14 and 14 are arranged in virtual planes orthogonal to the central axis of the housing 6 and are inclined at a predetermined angle in the same direction with respect to the radial direction of the housing 6. Yes. Then, the upstream end openings of the turbine air nozzle holes 14 and 14 are communicated with the turbine air supply passage 15 formed over the entire circumference in the vicinity of the outer periphery of the base end portion of the housing 6, and the turbine air supply. One place in the circumferential direction of the passage 15 is communicated with a turbine air supply port 16 provided in a state of opening in the base end face of the housing 6. Further, the downstream end openings (turbine air outlets) of the turbine air nozzle holes 14 and 14 are respectively opened on the inner peripheral surface of the base end portion of the housing 6. As a result, the downstream end openings of the turbine air nozzle holes 14 and 14 are opposed to the plurality of turbine blades 5 and 5 provided on the outer peripheral surface of the impeller body 4, respectively.

  In addition, a brake air nozzle hole 17 is formed in a portion of the base end portion of the housing 6 in which the turbine air nozzle holes 14 and 14 are formed, in a portion that is separated from the turbine air nozzle holes 14 and 14 in the circumferential direction. ing. The central axis of the brake air nozzle hole 17 is disposed in the same virtual plane as the central axis of the turbine air nozzle holes 14, 14, and the turbine air nozzle holes 14, 14 is inclined at a predetermined angle in a direction opposite to the central axis. Then, the upstream end opening of the brake air nozzle hole 17 is communicated with a brake air supply port 18 provided in a state of opening on the base end surface of the housing 6, and the downstream end opening (brake air) of the brake air nozzle hole 17 is provided. A jet outlet is opened on the inner peripheral surface of the base end portion of the housing 6. Thereby, the downstream end opening of the brake air nozzle hole 17 is made to face and oppose the plurality of turbine blades 5 and 5 provided on the outer peripheral surface of the impeller body 4.

  An annular rotation detection sensor 19 is supported and fixed to a portion of the housing 6 near the base end and located radially inward of the axial bearing member 11. Then, by making the detection surface (the right side surface in FIG. 4) of the rotation detection sensor 19 approach the encoder (not shown) provided on the other side surface (the left side surface in FIG. 4) of the impeller 2, A rotation detection device for detecting rotation information such as the rotation speed of the impeller 2 is configured.

When the surface to be coated is to be painted in a state where the electrostatic spray gun is completed using the spindle device with an air turbine configured as described above, the main shaft 1 is attached to the housing 6 as described above. The impeller 2 is rotatably supported by radial and axial static pressure gas bearings 7 and 8. In this state, compressed air is fed into the plurality of turbine air nozzle holes 14 and 14 through the turbine air supply port 16 and the turbine air supply passage 15. Then, the compressed air is ejected from the downstream end openings of the turbine air nozzle holes 14 and 14 and blown to a plurality of turbine blades 5 and 5 formed on the outer peripheral surface of the impeller body 4. As a result, the impeller 2 and the main shaft 1 are rotated at a high speed in the forward rotation direction (in the direction of arrow A in FIG. 5) at a rotational speed of about several tens of thousands min ⁻¹ . Then, in this state, through a paint supply pipe (not shown) inserted inside the main shaft 1, the front end portion (left end portion in FIG. 4) of the main shaft 1 is coupled to a portion protruding outside the housing 6. The paint is fed into a cup (not shown) fixed and passed through the negative electrode. Then, in the cup that rotates at high speed together with the main shaft 1, the paint is made into ionic fine particles. Then, the ionized fine particles are applied to the surface to be coated through the positive electrode by using an electrostatic attraction force and adhered to the surface to be coated. The air blown to the turbine blades 5 and 5 is the base end of the annular space 20 existing between the inner peripheral surface of the base end portion of the housing 6 and the outer peripheral surface of the impeller body 4 (FIG. 4). From the right end) through the exhaust passage (not shown) provided in communication with the base end opening.

  When stopping the painting operation on the surface to be coated, the supply of compressed air to the turbine nozzle holes 14 and 14 and the supply of paint into the cup are stopped and brake air is supplied. Compressed air is fed into the brake air nozzle hole 7 through the supply port 18. The compressed air is ejected from the downstream end opening of the brake air nozzle hole 17 and blown to the turbine blades 5 and 5. Thereby, the rotation of the impeller 2 and the main shaft 1 is stopped early by applying to the impeller 2 a force in the direction in which the forward rotation (rotation) is stopped (the direction of arrow B in FIG. 5). When the rotation detection sensor 19 confirms that the rotation of the main shaft 1 and the impeller 2 is stopped, the supply of compressed air to the brake air nozzle hole 7 is stopped. Note that the air blown to the turbine blades 5 and 5 as described above is also discharged from the proximal end opening of the annular space 20 to the external space through the exhaust passage.

  In the case of the first example of the conventional structure as described above, the downstream end openings of the turbine air nozzle holes 14 and 14 and the brake air nozzle hole 17 are respectively close to and opposed to the outer peripheral surface of the impeller body 4. The inner peripheral surface of the base end portion of the housing 6 is closely opposed to the outer peripheral surface of the impeller body 4 over the entire periphery. For this reason, the width dimension in the radial direction of the annular space 20 existing between the two peripheral surfaces is small over the entire circumference. However, when the radial width dimension of the annular space 20 is reduced over the entire circumference in this way, the compressed air ejected from the downstream end openings to the annular space 20 is discharged from the annular space 20. Since it becomes difficult to discharge into the exhaust passage, the pressure in the annular space 20 tends to increase. When the pressure in the annular space 20 is increased in this way, when the compressed air is ejected from the respective downstream end openings to the annular space 20, the compressed air cannot be sufficiently expanded (the back pressure increases, The kinetic energy at the air nozzle holes 14 and 17 is reduced. As a result, the driving efficiency and stopping efficiency of the impeller 2 cannot be sufficiently secured, which is not preferable.

  On the other hand, in Patent Document 1, as shown in FIG. 6, recesses 21 and 21 are respectively provided at a plurality of locations out of the respective downstream end openings in the circumferential direction on the inner peripheral surface of the base end portion of the housing 6 a. The invention to be formed is described. In the case of the second example having such a conventional structure, the radial width of the annular space 20a is increased at the portion where the recesses 21 and 21 are formed, and the downstream of each air nozzle hole 14 and 17 is accordingly increased. The compressed air ejected from the end opening to the annular space 20a can be easily discharged from the annular space 20a to the exhaust passage. Therefore, the pressure in the annular space 20a can be reduced, and the compressed air can be expanded more when the compressed air is ejected from the downstream end opening into the annular space 20a. As a result, the back pressure of the air nozzle holes 14 and 17 can be kept low, and the drive efficiency and stop efficiency of the impeller 2 can be improved.

  However, in the case of the second example of the conventional structure described above, the width dimension of the peripheral portion of the annular space 20a (the portion that is separated from the recesses 21 and 21 in the circumferential direction) of the downstream end opening. But it is still getting smaller. On the other hand, in order to further improve the driving efficiency and stopping efficiency of the impeller 2, the radial width of the annular space 20a is set to the entire circumference including the peripheral portion of each downstream end opening. It is hoped that you can make it bigger.

JP-A-6-313428

  In view of the circumstances as described above, the spindle device with an air turbine according to the present invention is configured such that the radial width dimension of the annular space existing between the inner peripheral surface of the housing and the outer peripheral surface of the impeller is set as a turbine air ejection hole. The invention was invented to realize a structure that can be enlarged over the entire circumference including the peripheral portion of (and the brake air ejection hole).

The spindle device with an air turbine of the present invention includes a housing, a main shaft that is inserted inside the housing, and a portion of the main shaft that is concentrically fixed to the main shaft (coupled or fixed). An impeller having a plurality of turbine blades formed on the outer peripheral surface, a hydrostatic gas bearing for rotatably supporting the main shaft and the impeller inside the housing, and an outer periphery of the impeller. One or a plurality of turbine air outlets that are provided in a portion that is close to and opposed to a part of the surface, and that ejects compressed air in a direction in which the impeller rotates forward toward the turbine blades.
In particular, in the spindle apparatus with an air turbine of the present invention, one or a plurality of turbine air nozzles protrude from the inner peripheral surface of the housing, and the tip openings of the turbine air nozzles serve as the turbine air outlets.

  As described above, in the case of the turbine-equipped spindle device of the present invention, the front end opening of the turbine air nozzle that protrudes from the inner peripheral surface of the housing serves as a turbine air outlet, and this turbine air outlet serves as the outer peripheral surface of the impeller. Adopting a structure that is close to each other. Therefore, the radial width dimension of the annular space existing between the outer peripheral surface of the impeller and the inner peripheral surface of the housing can be increased over the entire circumference. Accordingly, the compressed air ejected from the turbine air outlet to the annular space can be easily discharged from the annular space to the exhaust passage that leads to the external space, so that the pressure in the annular space can be hardly increased. Accordingly, when the compressed air is ejected from the turbine air ejection port into the annular space, the compressed air can be sufficiently expanded. As a result, the back pressure of the turbine air outlet can be kept low, the kinetic energy of the air ejected from the turbine air outlet can be increased, and the driving efficiency of the impeller can be sufficiently improved.

In the case of implementing the spindle device with an air turbine of the present invention, each of them may be a part of the outer peripheral surface of the impeller in the circumferential direction (the same or different part from the part facing the turbine air outlet). ) Is provided with one or more brake air outlets for jetting compressed air in a direction to stop the forward rotation of the impeller toward a plurality of turbine blades formed on the outer peripheral surface of the impeller. In this case, preferably, as described in claim 2, one or a plurality of brake air nozzles are protruded from a portion other than a portion where the turbine air nozzle is protruded on the inner peripheral surface of the housing, and the front ends of the brake air nozzles are opened. Are the brake air outlets.
If such a structure is employ | adopted, the stop efficiency of the said impeller can fully be improved.

Further, when the invention described in claim 2 is carried out, preferably, as described in claim 3, the shape of the edge opening edge of the brake air nozzle is assumed to be a virtual axis with the central axis of the impeller as its central axis. The shape is along a cylindrical surface or a tangent plane to the virtual cylindrical surface.
By adopting such a configuration, the peripheral edge portion of the tip opening of the brake air nozzle can be placed close to and opposed to the outer peripheral surface of the impeller at a substantially uniform distance over the entire circumference. For this reason, the compressed air which ejected from the front-end | tip opening of the said brake air nozzle can be efficiently sprayed on the some turbine blade formed in the outer peripheral surface of the said impeller. Therefore, the stop efficiency of the impeller can be sufficiently improved.

In carrying out the invention according to any one of claims 1 to 3, preferably, as described in claim 4, the shape of the edge opening edge of the turbine air nozzle is set to the central axis of the impeller. And a shape along a virtual cylindrical surface having a central axis thereof or a tangential plane to the virtual cylindrical surface.
By adopting such a configuration, the peripheral edge portion of the tip opening of the turbine air nozzle can be placed close to and opposed to the outer peripheral surface of the impeller at a substantially uniform distance over the entire circumference. For this reason, the compressed air which ejected from the front-end | tip opening of the said turbine air nozzle can be efficiently sprayed on the some turbine blade formed in the outer peripheral surface of the said impeller. Accordingly, the driving efficiency of the impeller can be sufficiently improved.

  1 and 2 show a first embodiment of the present invention corresponding to claims 1 and 2. The feature of this embodiment is the structure of the inner peripheral surface portion of the base end portion of the housing 6b facing the outer peripheral surface of the impeller body 4. Since the structure and operation of the other parts are the same as those in the first example of the conventional structure shown in FIGS. 4 to 5 described above, the same parts are denoted by the same reference numerals, and redundant description is omitted or simplified. Hereinafter, the characteristic part of the present embodiment will be mainly described.

  In the case of this embodiment, the diameter of the inner peripheral surface of the base end portion of the housing 6 b facing the outer peripheral surface of the impeller body 4 is sufficiently larger than the diameter of the outer peripheral surface of the impeller body 4. As a result, the width dimension in the radial direction of the annular space 20b existing between the two peripheral surfaces is sufficiently increased over the entire circumference.

  In the case of this embodiment, the base end portions of the tubular turbine air nozzles 22, 22 are respectively provided at the downstream end portions of the turbine air nozzle holes 14, 14, and the base portion of the circular tubular brake air nozzle 23 is provided at the brake air nozzle hole 17. The end portions are each press-fitted and fixed (fixed with an interference fit). Thereby, the tip opening of each of the turbine air nozzles 22, 22 projecting from the inner peripheral surface of the base end portion of the housing 6 b is a turbine air nozzle ejection hole, and the tip opening of the brake air nozzle 23 is a brake air nozzle ejection hole. The front end openings of the turbine air nozzles 22 and 22 and the front end openings of the brake air nozzles 23 are respectively close to and opposed to the outer peripheral surface of the impeller body 4. In the case of the present embodiment, the shape of the peripheral edge portion of the tip opening of each turbine air nozzle 22, 22 and the shape of the peripheral edge portion of the tip opening of the brake air nozzle 23 are orthogonal to the central axes of the nozzles 22, 23, respectively. The shape is along a virtual plane. Moreover, when implementing this invention, the base end part of each said nozzle 22 and 23 can also be adhere | attached fixation and screwed fixation to each said nozzle hole 14 and 17. FIG.

  As described above, in the case of the spindle device with a turbine according to the present embodiment, the radial width dimension of the annular space 20b existing between the outer peripheral surface of the impeller body 4 and the base end portion inner peripheral surface of the housing 6b. Can be increased over the entire circumference. For this reason, the compressed air jetted into the annular space 20b from the front end openings of the turbine air nozzles 22 and 22 and the front end opening of the brake air nozzle 23 is supplied from the base end (right end in FIG. 1) opening of the annular space 20b. The exhaust passage (not shown) provided in communication with the base end opening can be easily discharged. Therefore, it is difficult to increase the pressure in the annular space 20b. Therefore, when the compressed air is ejected from the front end openings of the turbine air nozzles 22 and 22 and the front end opening of the brake air nozzle 23 to the annular space 20b, the compressed air can be sufficiently expanded. As a result, the back pressure related to the nozzles 22 and 23 is suppressed to a small level, and the kinetic energy of the compressed air ejected from the tip openings of the nozzles 22 and 23 is secured, so that the driving efficiency and stopping efficiency of the impeller 2 are sufficiently high Can be improved.

  Next, FIG. 3 shows Embodiment 2 of the present invention corresponding to claims 1 to 4. In the case of the present embodiment, the shape of the peripheral edge of the front end opening of each turbine air nozzle 22a, 22a and the shape of the peripheral edge of the front end opening of the brake air nozzle 23a are respectively centered on the central axis of the impeller body 4. The shape is along the virtual cylindrical surface α. In the case of the present embodiment configured as described above, the tip opening peripheral edge of each of the turbine air nozzles 22a and 22a and the tip opening peripheral edge of the brake air nozzle 23a are spread over the entire periphery, respectively, and the impeller body 4 It is possible to make them face and face each other at a uniform distance. For this reason, in the case of the present embodiment, the compressed air ejected from each of the tip openings can be efficiently blown to the plurality of turbine blades 5 and 5 provided on the outer peripheral surface of the impeller body 4. Therefore, in the case of the present embodiment, the driving efficiency and the stopping efficiency of the impeller 2 can be more sufficiently improved. Other configurations and operations are the same as those of the first embodiment described above.

Sectional drawing which shows Example 1 of this invention. AA sectional drawing of FIG. The figure similar to FIG. 2 which shows Example 2 of this invention. Sectional drawing which shows the 1st example of a conventional structure. BB sectional drawing of FIG. The figure similar to FIG. 5 which shows the 2nd example of conventional structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main axis | shaft 2 Impeller 3 Ring part 4 Impeller body 5 Turbine blade 6, 6a, 6b Housing 7 Radial static pressure gas bearing 8 Axial static pressure gas bearing 9 Radial bearing member 10 Air supply passage 11 Axial bearing member 12 Exhaust hole 13 Exhaust passage 14 Turbine air nozzle hole 15 Turbine air supply passage 16 Turbine air supply port 17 Brake air nozzle hole 18 Brake air supply port 19 Rotation detection sensor 20, 20a, 20b Annular space 21 Concave portion 22, 22a Turbine air nozzle 23, 23a Brake air nozzle

Claims (4)

  A housing, a main shaft inserted through the inside of the housing, and an impeller having a plurality of turbine blades formed on the outer peripheral surface, concentrically fixed to a portion of the main shaft disposed inside the housing, concentrically with the main shaft A hydrostatic gas bearing for rotatably supporting the main shaft and the impeller on the inner side of the housing, and each of the turbine blades is provided in a portion facing and facing a part of the outer peripheral surface of the impeller. In the spindle apparatus with an air turbine provided with one or more turbine air outlets for ejecting compressed air in a direction in which the impeller rotates in the forward direction, one or more A spindle apparatus with an air turbine in which a turbine air nozzle is protruded, and a tip opening of each turbine air nozzle is used as each turbine air outlet.   Compressed air in a direction to stop the forward rotation of the impeller is directed to a plurality of turbine blades formed on the outer peripheral surface of the impeller at portions facing each other in the circumferential direction of the outer peripheral surface of the impeller. One or a plurality of brake air outlets for jetting are provided, and one or a plurality of brake air nozzles are protruded from a portion other than a portion where the turbine air nozzle is protruded on the inner peripheral surface of the housing, and front end openings of the respective brake air nozzles The spindle device with an air turbine according to claim 1, wherein each of the brake air ejection ports is defined as the above.   The spindle with an air turbine according to claim 2, wherein the edge of the opening edge of the brake air nozzle has a shape along a virtual cylindrical surface having a central axis of the impeller as a central axis or a tangential plane to the virtual cylindrical surface. apparatus.   The shape of the edge opening edge part of a turbine air nozzle is made into the shape along the tangential plane with respect to the virtual cylindrical surface which uses the central axis of an impeller as the central axis, or this virtual cylindrical surface. Spindle device with air turbine described in 1.

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