JP2006336826A - Hydrostatic gas bearing spindle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrostatic gas bearing spindle capable of preventing intrusion of foreign matter such as working fluid to a hydrostatic gas bearing even after the operation is terminated. <P>SOLUTION: This hydrostatic gas bearing spindle 1 includes a communication passage 70 for communicating a hydrostatic gas journal bearing 31, a hydrostatic gas thrust bearing 32 and the external of the hydrostatic gas bearing spindle 1, a sealing gas supply portion 50 for supplying a sealing gas to the communication passage 70 for preventing inflow of the foreign matter to the hydrostatic gas journal bearing 31 and the hydrostatic gas thrust bearing 32, and a sealing gas flow channel 51 connecting the communication passage 70 and the seal gas supply portion 50. The communication passage 70 is provided with a liquid storing portion between a first connecting portion as a connecting portion with the sealing gas flow channel 51 and a communication passage opening as an opening to the external of the hydrostatic gas bearing spindle 1 in the communication passage 70. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrostatic gas bearing spindle, and more particularly to a hydrostatic gas bearing spindle provided with a sealing gas supply unit for preventing foreign matter from flowing into the hydrostatic gas bearing.

  A static pressure gas bearing spindle used for a processing machine such as a machine tool is often used in an environment where splashes of grinding fluid, cutting fluid, and the like (hereinafter referred to as processing fluid) are scattered. In such a case, during operation of the processing machine, the machining fluid containing chips of the workpiece may enter the bearing gap of the static pressure gas bearing, causing problems such as seizure of the static pressure gas bearing.

On the other hand, a hydrostatic gas bearing spindle provided with a sealing mechanism using compressed air has been proposed. This prevents the machining fluid from entering the static pressure gas bearing during operation of the static pressure gas bearing spindle, that is, while compressed air is supplied to the sealing mechanism and the static pressure gas bearing (for example, Patent Documents). 1).
JP 2000-46054 A

  However, when the operation of the hydrostatic gas bearing spindle is completed and the supply of compressed air to the sealing mechanism and hydrostatic gas bearing is stopped, the working fluid adhering to the hydrostatic gas bearing spindle is transferred to the hydrostatic gas bearing by capillary action. There is a risk of intrusion. Furthermore, the gas inside the spindle, whose temperature has been raised by the operation of the hydrostatic gas bearing spindle, is contracted by being cooled after the operation is stopped, and the inside of the spindle becomes a negative pressure with respect to the outside of the spindle. Therefore, there is a possibility that the machining fluid adhering to the static pressure gas bearing spindle may enter the static pressure gas bearing inside the spindle together with air. When the machining fluid enters the static pressure gas bearing in this manner, there is a risk that problems such as seizure of the static pressure gas bearing may occur if the operation of the static pressure gas bearing spindle is resumed.

  Accordingly, an object of the present invention is to provide a static pressure gas bearing spindle capable of preventing foreign matter such as machining fluid from entering the static pressure gas bearing even after the operation is completed.

  A hydrostatic gas bearing spindle according to the present invention is a hydrostatic gas bearing spindle provided with a hydrostatic gas bearing, wherein the hydrostatic gas bearing communicates with the outside of the hydrostatic gas bearing spindle, A sealing gas supply section for supplying a sealing gas to the communication path in order to prevent foreign matter from flowing into the gas bearing; and a sealing gas flow path connecting the communication path and the sealing gas supply section. Yes. In the communication passage, a liquid reservoir is formed between the first connection portion which is a connection portion with the sealing gas flow path and the communication passage opening which is an opening to the outside of the static pressure gas bearing spindle in the communication passage. ing.

  According to the static pressure gas bearing spindle of the present invention, during operation of the static pressure gas bearing spindle, the sealing gas is supplied from the sealing gas supply portion to the communication path through the sealing gas flow path, Inflow of foreign matter to the static pressure gas bearing is prevented. On the other hand, when the operation of the static pressure gas bearing spindle is finished and the supply of the sealing gas to the communication path is stopped, the communication path opening is caused by capillary action, negative pressure inside the static pressure gas bearing spindle, etc. There is a risk that foreign matter such as machining fluid may enter. However, even when foreign matter such as machining fluid enters, foreign matter such as the entered machining fluid is captured and collected in the liquid reservoir. For this reason, foreign matter such as machining fluid hardly enters the hydrostatic gas bearing side (upstream side in the discharge direction of the sealing gas) from the liquid reservoir, and even if it enters slightly, the surface tension causes the vicinity of the liquid reservoir. It is held and entry into the hydrostatic gas bearing is suppressed. As a result, it is possible to provide a hydrostatic gas bearing spindle capable of preventing foreign matter such as machining fluid from entering the hydrostatic gas bearing even after the operation is completed.

  Here, in the static pressure gas bearing spindle including a rotating portion and a housing adjacent to surround the rotating portion, for example, the communication path is a gap between the rotating portion and the housing, and is a static pressure gas bearing and a static pressure. A passage communicating with the outside of the gas bearing spindle.

  Preferably, the hydrostatic gas bearing spindle further includes a liquid discharge path that connects the liquid reservoir and the outside of the hydrostatic gas bearing spindle. As a result, foreign matter such as machining fluid accumulated in the liquid reservoir is restarted by the operation of the static pressure gas bearing spindle, and the sealing gas is supplied to the communication path, so that the static pressure gas bearing passes through the liquid discharge path. It is discharged to the outside of the spindle. As a result, it is not necessary to separately perform a work for removing foreign substances such as machining fluid accumulated in the liquid reservoir, and maintenance of the static pressure gas bearing spindle is facilitated.

  Preferably, in the static pressure gas bearing spindle, the cross-sectional area of the cross section perpendicular to the gas flow in the liquid discharge path is greater than the cross-sectional area of the cross section perpendicular to the gas flow in the communication path on the communication path opening side of the liquid reservoir. Is also small.

  Thereby, the quantity of the gas for sealing discharged | emitted through the liquid discharge path to the exterior of a static pressure gas bearing spindle can be suppressed. As a result, it is possible to reduce the influence on the sealing performance by providing the liquid discharge path.

  In the hydrostatic gas bearing spindle, preferably, the liquid reservoir includes an upstream connection opening that is a connection portion with a communication path located upstream in the discharge direction of the sealing gas in the communication path, and a downstream in the discharge direction. A downstream connection opening which is a connection portion with the communication path located on the side is formed. The downstream connection opening is arranged at a position that does not overlap the upstream connection opening in a plan view when viewed from the direction along the supply direction of the sealing gas supplied from the upstream connection opening to the liquid reservoir.

  As a result, foreign matter such as machining fluid that has entered the liquid reservoir from the downstream connection opening is less likely to directly enter the upstream connection opening, and is thus easily captured by the liquid reservoir. As a result, the penetration of the working fluid that has entered the liquid reservoir into the static pressure gas bearing is further suppressed.

  Preferably, the static pressure gas bearing spindle further includes a pressure adjusting discharge path connected between the static pressure gas bearing and the first connecting portion in the communication path and connecting the communication path and the outside. The resistance to the gas flow between the second connecting portion and the first connecting portion, which is the connecting portion between the communication passage and the pressure adjusting discharge passage, is larger than the resistance to the gas flow in the pressure adjusting discharge passage. Thus, the communication path and the pressure adjusting discharge path are configured.

  When the pressure of the sealing gas in the communication path increases, the pressure at the outer periphery of the hydrostatic gas bearing increases, which affects the pressure distribution in the bearing clearance of the hydrostatic gas bearing, changes in the steady position of rotation of the rotating part, and rigidity There is a risk that problems such as lowering (decrease in rotational runout accuracy of the rotating part) may occur. In particular, in order to improve the sealing performance, such a problem is likely to occur when the supply pressure of a sealing gas such as compressed air is increased, or when the width of the communication path is reduced. On the other hand, the communication passage and the pressure adjusting discharge passage are configured as described above, so that the pressure around the hydrostatic gas bearing is almost equal to the pressure outside the spindle even when the pressure of the sealing gas is increased. Kept. As a result, it is possible to suppress the occurrence of problems caused by the sealing gas affecting the pressure distribution in the bearing gap of the static pressure gas bearing.

  In the hydrostatic gas bearing spindle, preferably, the resistance to the gas flow between the second connecting portion and the first connecting portion, which is a connecting portion between the communication passage and the pressure adjusting discharge passage, is the liquid reservoir portion. The communication path is configured to be larger than the resistance against the gas flow between the first connecting portion and the first connecting portion.

  As a result, the sealing gas necessary for ensuring the sealing performance is ejected from the communication passage opening through a path having a low resistance to the gas flow, and excessive sealing gas is passed through a path having a high resistance to the gas flow. And discharged outside the static pressure gas bearing spindle. As a result, it is possible to avoid a decrease in sealing performance due to the provision of the pressure adjusting discharge passage.

  As is apparent from the above description, according to the hydrostatic gas bearing spindle of the present invention, the hydrostatic gas bearing spindle capable of preventing foreign matter such as machining fluid from entering the hydrostatic gas bearing even after the operation is completed. Can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing a configuration of a static pressure gas bearing spindle according to Embodiment 1, which is an embodiment of the present invention. FIG. 2 is a schematic partial cross-sectional view showing the vicinity of region II in FIG. 1 in an enlarged manner. With reference to FIG. 1 and FIG. 2, the structure of the static pressure gas bearing spindle of Embodiment 1 is demonstrated.

  Referring to FIG. 1, the static pressure gas bearing spindle 1 of Embodiment 1 includes a rotating part 10 and a housing part 20 formed so as to surround the rotating part 10. Between the rotating part 10 and the housing part 20, a hydrostatic gas journal bearing 31 that supports the rotating part 10 in a direction perpendicular to the axis (radial direction) and an axis of the rotating part 10 in the axial direction (axial direction) are provided. A supporting hydrostatic gas thrust bearing 32 is arranged. Further, the static pressure gas bearing spindle 1 includes a bearing gas supply unit 40, and a bearing gas such as air supplied from a bearing gas supply source such as an air compressor (not shown) to the bearing gas supply unit 40 is a bearing. The gas supply passage 33 is supplied to the static pressure gas journal bearing 31 and the static pressure gas thrust bearing 32 through the journal supply throttle 31A and the thrust supply throttle 32A. Thus, a gas film is formed by the supplied bearing gas in the gap between the rotating portion 10 and the housing portion 20, and the rotating portion 10 is pivotally supported with respect to the housing portion 20. A rotor 60 of the motor is disposed in the rotating unit 10, and the rotating unit 10 is configured to be rotatable by the power of the motor.

  Further, the static pressure gas bearing spindle 1 includes a static pressure gas journal bearing 31, a static pressure gas thrust bearing 32 and a communication passage 70 that communicates the outside of the static pressure gas bearing spindle 1 and the inflow of foreign matter to the static pressure gas bearing portion. In order to prevent this, a sealing gas supply part 50 for supplying a sealing gas to the communication path 70 and a sealing gas flow channel 51 connecting the communication path 70 and the sealing gas supply part 50 are included.

  Referring to FIG. 2, the communication passage 70 is a first connection portion 71 that is a connection portion with the sealing gas flow path 51 and a communication passage that is an opening to the outside of the static pressure gas bearing spindle 1 in the communication passage 70. A liquid reservoir 73 is formed between the passage opening 72. Here, the communication passage 70 includes a communication passage opening 72, a first seal gap 77 that connects the communication passage opening 72 and the liquid reservoir 73, a liquid reservoir 73, and a liquid reservoir from the outside of the static pressure gas bearing spindle 1. The second seal gap 78 connecting 73 and the first connecting portion 71, the first connecting portion 71, and the third seal gap 79 connecting the first connecting portion 71 and the static pressure gas bearing portion via static pressure. It is formed so as to reach the gas bearing portion. Moreover, the cross section perpendicular | vertical to the axial direction of the rotation part 10 is circular. The communication passage 70 and the liquid reservoir 73 are formed along the rotating portion 10, and the cross section perpendicular to the axial direction has an annular shape.

  Further, the static pressure gas bearing spindle 1 is provided with a liquid discharge passage 90 that connects the liquid reservoir 73 and the outside of the static pressure gas bearing spindle 1. The cross-sectional area of the cross section perpendicular to the direction of the gas flow in the liquid discharge path 90 is the direction of the gas flow in the communication path 70 (first seal gap 77) on the communication path opening 72 side of the liquid reservoir 73. Smaller than the cross-sectional area of the cross section perpendicular to. Furthermore, the sum of the cross-sectional areas of the liquid discharge passage 90 and the first seal gap 77 in the cross section perpendicular to the direction of gas flow is the cross-sectional area of the cross section of the second seal gap 78 perpendicular to the direction of gas flow. Smaller than.

  Furthermore, the liquid reservoir 73 is positioned on the downstream side in the discharge direction and the upstream side connection opening 74 that is a connection part with the communication path 70 located on the upstream side in the discharge direction of the sealing gas in the communication path 70. A downstream connection opening 75 which is a connection portion with the communication path 70 is formed. The downstream connection opening 75 is disposed at a position that does not overlap the upstream connection opening 74 in a plan view when viewed from the direction along the supply direction 76 of the sealing gas supplied from the upstream connection opening 74 to the liquid reservoir 73. Has been. From another viewpoint, the communication path 70 is bent at the liquid reservoir 73.

  Next, the operation of the static pressure gas bearing spindle 1 according to the first embodiment will be described with reference to FIGS. 1 and 2. Referring to FIG. 1, a rotational driving force is generated by supplying electric power from a power source (not shown) to a motor having a rotor 60 of the motor. Thereby, the rotating part 10 that is pivotally supported with respect to the housing part 20 rotates relative to the housing part 20.

  At this time, a sealing gas is supplied to the sealing gas supply unit 50 from a sealing gas supply source such as an air compressor (not shown). The sealing gas supplied to the sealing gas supply unit 50 passes through the sealing gas flow channel 51 and reaches the communication path 70 in the first connecting unit 71 as shown in FIG. Then, the sealing gas is ejected from the communication passage opening 72 toward the outside of the static pressure gas bearing spindle 1 through the second seal gap 78, the liquid reservoir 73, and the first seal gap 77. As a result, during operation of the static pressure gas bearing spindle 1, entry of the machining fluid into the communication path 70 is prevented even when the machining fluid is used in an environment in which splashing occurs.

  On the other hand, in the state where the operation of the static pressure gas bearing spindle 1 is finished and the ejection of the sealing gas is stopped, the temperature of the static pressure gas bearing spindle 1 whose temperature has been increased by the operation decreases, and thereby the communication path 70 is reduced. The temperature of the internal gas decreases and contracts, and the inside of the communication passage 70 is in a negative pressure state with respect to the outside of the static pressure gas bearing spindle 1. As a result, there is a possibility that the machining fluid containing chips adhering to the periphery of the communication path opening 72 may enter the communication path 70. In addition, the machining liquid may enter the communication path 70 due to capillary action. However, in the static pressure gas bearing spindle 1, since the liquid reservoir 73 is formed between the first connection portion 71 and the communication passage opening 72 in the communication passage 70, the first passage 71 is connected to the first passage 71. The machining liquid that has entered through the seal gap 77 is captured by the liquid reservoir 73. For this reason, the machining liquid hardly penetrates into the second seal gap 78. Even when the machining liquid slightly enters the second seal gap 78, the machining liquid is held in the second seal gap 78 due to surface tension. As a result, in the static pressure gas bearing spindle 1, the penetration of the machining fluid that has entered the communication path 70 into the static pressure gas journal bearing 31 and the static pressure gas thrust bearing 32 is suppressed.

  Furthermore, as described above, the static pressure gas bearing spindle 1 of the first embodiment includes the liquid discharge path 90 that connects the liquid reservoir 73 and the outside of the static pressure gas bearing spindle 1. Therefore, when the operation of the static pressure gas bearing spindle 1 is restarted and the sealing gas is supplied to the communication path 70, the machining liquid accumulated in the liquid reservoir 73 passes through the liquid discharge path 90 and is then static pressure gas bearing spindle. 1 is discharged to the outside. As a result, it is not necessary to separately perform the work of removing the machining liquid accumulated in the liquid reservoir 73, and maintenance (maintenance) of the static pressure gas bearing spindle 1 is facilitated. Here, at least one liquid discharge path 90 may be formed, but it is more preferable that a plurality of liquid discharge paths 90 be formed in order to efficiently discharge the machining liquid. In the case where a plurality of liquid discharge channels are formed, the liquid discharge path 90 is disposed at a position where the discharged liquid does not adversely affect the surroundings and the scattered droplets or mist of the processing liquid does not easily enter the liquid discharge path 90. It is desirable that Furthermore, a porous member such as a sintered metal or a porous resin may be disposed in the vicinity of the outlet of the liquid discharge path 90 (position adjacent to the outlet) in order to prevent the processing liquid from entering.

  Furthermore, as described above, the cross-sectional area of the cross section perpendicular to the gas flow in the liquid discharge passage 90 is smaller than the cross-sectional area of the cross section of the first seal gap 77 perpendicular to the gas flow direction. Therefore, the amount of sealing gas discharged to the outside of the static pressure gas bearing spindle 1 through the liquid discharge passage 90 is suppressed. As a result, the influence on the sealing performance by providing the liquid discharge path 90 is reduced. Further, the sum of the cross-sectional areas of the liquid discharge passage 90 and the first seal gap 77 in the cross section perpendicular to the gas flow direction is the cross-sectional area of the second seal gap 78 in the cross section perpendicular to the gas flow direction. Smaller than. Therefore, the resistance of the second seal gap 78 to the gas flow is smaller than the resistance of the downstream portion of the second seal gap 78, and the pressure of the sealing gas in the liquid reservoir 73 is kept relatively high. As a result, the sealing gas is ejected from the first seal gap 77 at a high speed, and a better sealing performance can be realized.

  The communication path 70 and the liquid discharge path 90 may be configured such that the resistance to the gas flow in the liquid discharge path 90 is larger than the resistance to the gas flow in the first seal gap 77. Thereby, the amount of sealing gas discharged through the liquid discharge passage 90 to the outside of the static pressure gas bearing spindle 1 is suppressed. As a result, the influence on the sealing performance by providing the liquid discharge path 90 is reduced. Here, in order to make the resistance to the gas flow in the liquid discharge path 90 larger than the resistance to the gas flow in the first seal gap 77, for example, a cross section perpendicular to the direction of the gas flow in the liquid discharge path 90 is used. The cross-sectional area is made smaller than the cross-sectional area of the cross section perpendicular to the gas flow direction of the first seal gap 77. The length of the liquid discharge passage 90 is made longer than the length of the first seal gap 77 in the gas flow direction. Measures such as lengthening can be adopted.

  Further, as described above, the downstream connection opening 75 is arranged at a position that does not overlap the upstream connection opening 74 in a plan view when viewed from the direction along the supply direction 76 of the sealing gas. From another viewpoint, the communication path 70 is bent at the liquid reservoir 73. Therefore, the machining liquid that has entered the liquid reservoir 73 from the downstream connection opening 75 is less likely to directly enter the upstream connection opening 74, and is easily captured by the liquid reservoir 73. As a result, the penetration of the machining fluid that has entered the communication passage 70 into the static pressure gas journal bearing 31 and the static pressure gas thrust bearing 32 is further suppressed.

  As shown in FIG. 2, in the hydrostatic gas bearing spindle 1, the housing portion 20 is composed of a plurality of members, and the liquid reservoir 73 and the hydrostatic gas journal bearing 31 or the like are formed by a gap including a gap between the members. / And when the static pressure gas thrust bearing 32 communicates, it is preferable to arrange the O-ring 100 in at least one place of the gap. Accordingly, it is possible to prevent the machining fluid from entering the static pressure gas journal bearing 31 and / or the static pressure gas thrust bearing 32 from the liquid reservoir 73 through the gap.

(Embodiment 2)
FIG. 3 is a schematic partial cross-sectional view for explaining the configuration of the hydrostatic gas bearing spindle according to the second embodiment which is an embodiment of the present invention. With reference to FIG. 1 and FIG. 3, the structure of the static pressure gas bearing spindle of Embodiment 2 of this invention is demonstrated.

  The static pressure gas bearing spindle 1 of the second embodiment and the static pressure gas bearing spindle 1 of the first embodiment described above have basically the same configuration. However, the second embodiment is different from the first embodiment in that the region III in FIG. 1 has a configuration as shown in FIG.

  Specifically, referring to FIG. 3, the static pressure gas bearing spindle 1 according to the second embodiment includes a static pressure gas journal bearing 31, a static pressure gas thrust bearing 32, a first connection portion 71, and a communication path 70. The hydrostatic gas bearing of the first embodiment is further provided with a pressure adjusting discharge passage 80 that is connected to the third seal gap 79 that connects the communication path 70 and the outside of the hydrostatic gas bearing spindle 1. It is different from the spindle 1. That is, the pressure adjusting discharge passage 80 has a discharge passage 81, and one end of the discharge passage 81 is connected to the third seal gap 79 of the communication passage 70 at the second connecting portion 82. Further, the other end of the discharge passage 81 is connected to an exhaust passage 84 having an opening 83 to the outside of the static pressure gas bearing spindle 1.

  Further, the resistance to the gas flow in the third seal gap 79 between the second connecting portion 82 and the first connecting portion 71, which is a connecting portion between the communication passage 70 and the pressure adjusting discharge passage 80, is liquid. The communication path 70 is configured to be larger than the resistance against the gas flow in the second seal gap 78 connecting the reservoir 73 and the first connecting portion 71.

  Next, the operation of the hydrostatic gas bearing spindle 1 according to the second embodiment will be described with reference to FIGS. 1 and 3. The hydrostatic gas bearing spindle 1 of the second embodiment operates in the same manner as the hydrostatic gas bearing spindle 1 of the first embodiment, and the intrusion of the machining fluid into the communication path 70 is similarly prevented by the ejection of the sealing gas. ing. Further, the same is true for preventing the machining fluid from entering the communication path 70 after the operation of the static pressure gas bearing spindle 1 is stopped.

  Here, as described above, the static pressure gas bearing spindle 1 of the second embodiment is connected to the third seal gap 79 in the communication path 70 and connects the communication path 70 and the outside of the static pressure gas bearing spindle 1. A pressure adjusting discharge passage 80 is further provided. The resistance to the gas flow in the third seal gap 79 between the second connection portion 82 and the first connection portion 71 is larger than the resistance to the gas flow in the pressure adjusting discharge passage 80. In addition, a communication passage 70 and a pressure adjusting discharge passage 80 are formed. Therefore, the sealing gas supplied to the communication passage 70 is restricted from flowing out to the static pressure gas bearing side by the third seal gap 79, and the discharged sealing gas is discharged to the outside through the pressure adjusting discharge passage 80. Therefore, the pressure around the bearing clearance of the static pressure gas bearing is maintained at an atmospheric pressure outside the spindle. As a result, it is possible to suppress the occurrence of problems caused by the sealing gas affecting the pressure distribution between the bearing gaps of the static pressure gas journal bearing 31 and the static pressure gas thrust bearing 32.

  Further, as described above, the communication path 70 is configured such that the resistance to the gas flow in the third seal gap 79 is larger than the resistance to the gas flow in the second seal gap 78. Therefore, the sealing gas necessary for ensuring the sealing performance is ejected from the communication passage opening 72 to the outside of the static pressure gas bearing spindle 1 through the second seal gap 78 having a low resistance to the gas flow, and an excessive sealing gas. Reaches the pressure adjusting discharge passage 80 through the third seal gap 79 having a large resistance to the gas flow, and is discharged from the opening 83 to the outside of the hydrostatic gas bearing spindle 1. As a result, it is possible to avoid a decrease in sealing performance due to the provision of the pressure adjusting discharge passage 80.

  Here, as the resistance to the gas flow in the third seal gap 79 is larger, it is possible to suppress the occurrence of problems due to the influence on the performance of the static pressure gas bearing and to improve the seal performance. Therefore, the configuration of the communication path 70 can be determined so that the resistance to the gas flow in the third seal gap 79 is maximized within a range where no contact with the rotating unit 10 occurs. In order to make the resistance to the gas flow in the third seal gap 79 larger than the resistance to the gas flow in the second seal gap 78, for example, the cross section of the third seal gap 79 perpendicular to the gas flow is cut off. The area of the third seal gap 79 is smaller than the cross-sectional area of the second seal gap 78 perpendicular to the gas flow, and the length of the third seal gap 79 is longer than the length of the gas flow of the second seal gap 78 in the gas flow. Measures such as lengthening can be adopted.

  Further, the gas flow in the communication path 70 (third seal gap 79) between the second connection part 82 and the first connection part 71, which are the connection parts of the communication path 70 and the pressure adjusting discharge path 80. The cross-sectional area of the cross section perpendicular to the cross-sectional area is greater than the cross-sectional area of the cross section perpendicular to the direction of gas flow in the communication passage 70 (second seal gap 78) between the liquid reservoir 73 and the first connecting portion 71. You may comprise the communicating path 70 so that it may become small.

  In general, in the third seal gap 79 and the second seal gap 78, the cross-sectional area of the cross section perpendicular to the gas flow direction is smaller than that of the gas flow direction compared to other elements such as the length in the gas flow direction. The effect on resistance to flow is large. Therefore, the communication path 70 is configured such that the resistance to the gas flow in the third seal gap 79 is larger than the resistance to the gas flow in the second seal gap 78 by the configuration of the communication path 70 as described above. can do. As a result, it is possible to avoid a decrease in sealing performance due to the provision of the pressure adjusting discharge passage 80.

  The embodiment disclosed this time is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The hydrostatic gas bearing spindle of the present invention can be particularly advantageously applied to a hydrostatic gas bearing spindle provided with a sealing gas supply unit for preventing foreign substances from flowing into the hydrostatic gas bearing.

1 is a schematic cross-sectional view showing a configuration of a static pressure gas bearing spindle of a first embodiment. FIG. 2 is a schematic partial cross-sectional view showing an area around a region II in FIG. 1 in an enlarged manner. FIG. 6 is a schematic partial cross-sectional view for explaining a configuration of a static pressure gas bearing spindle of a second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Static pressure gas bearing spindle, 10 rotation part, 20 housing part, 31 Static pressure gas journal bearing, 32 Static pressure gas thrust bearing, 33 Gas supply path for bearings, 40 Gas supply part for bearings, 50 Gas supply part for seals, 51 Sealing gas flow path, 60 Motor rotor, 70 Communication path, 71 First connection part, 72 Communication path opening, 73 Liquid reservoir, 74 Upstream connection opening, 75 Downstream connection opening, 76 Sealing gas Supply direction, 77 first seal gap, 78 second seal gap, 79 third seal gap, 80 pressure adjusting discharge path, 81 discharge path, 82 second connecting portion, 83 opening to the outside, 84 Exhaust passage, 90 liquid discharge passage, 100 O-ring.

Claims (6)

A hydrostatic gas bearing spindle with hydrostatic gas bearings,
A communication passage communicating the static pressure gas bearing and the outside of the static pressure gas bearing spindle;
A sealing gas supply unit for supplying a sealing gas to the communication path in order to prevent inflow of foreign matter into the static pressure gas bearing;
A sealing gas flow path connecting the communication path and the sealing gas supply unit;
In the communication passage, a liquid reservoir is provided between a first connection portion that is a connection portion with the sealing gas flow path and a communication passage opening that is an opening to the outside of the static pressure gas bearing spindle in the communication passage. A hydrostatic gas bearing spindle in which the part is formed.   The hydrostatic gas bearing spindle according to claim 1, further comprising a liquid discharge path that connects the liquid reservoir and the outside of the hydrostatic gas bearing spindle.   The cross-sectional area of the cross section perpendicular to the gas flow in the liquid discharge path is smaller than the cross-sectional area of the cross section perpendicular to the gas flow in the communication path on the communication path opening side than the liquid reservoir. Or a hydrostatic gas bearing spindle according to 2; In the liquid reservoir,
An upstream connection opening which is a connection portion with the communication path located on the upstream side in the discharge direction of the sealing gas in the communication path;
A downstream connection opening that is a connection portion with the communication path located on the downstream side in the discharge direction is formed;
The downstream connection opening is arranged at a position that does not overlap the upstream connection opening in a plan view when viewed from the direction along the supply direction of the sealing gas supplied from the upstream connection opening to the liquid reservoir. The hydrostatic gas bearing spindle according to any one of claims 1 to 3. The communication path further includes a pressure adjusting discharge path that is connected between the static pressure gas bearing and the first connection portion and connects the communication path and the outside.
The resistance to the gas flow between the second connecting portion and the first connecting portion, which is the connecting portion between the communication passage and the pressure adjusting discharge passage, is against the gas flow in the pressure adjusting discharge passage. The hydrostatic gas bearing spindle according to any one of claims 1 to 4, wherein the communication path and the pressure adjusting discharge path are configured to be larger than a resistance.   The resistance to the gas flow between the second connection part and the first connection part is larger than the resistance to the gas flow between the liquid reservoir part and the first connection part. The hydrostatic gas bearing spindle according to claim 5, wherein the communication path is configured.

Images