JP2003074550A - Foil gas bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foil gas bearing controlling frictional force by keeping in contact with a rotary shaft and bearing material when an instrument stops and goes, and capable of precisely maintaining a bearing clearance between the rotary shaft and bearing material by simply and accurately installing a back-spring to the bearing material, and capable of adjusting the bearing clearance during an assembling state and an operating state of the bearing, and capable of adjusting a high temperature member without any trouble by improving a heat-resistant property by making maximum temperature in use of the bearing material increased. SOLUTION: In the foil gas bearing supporting the back-spring made of a thin sheet on an inner surface side of a bearing housing and supporting the thin sheet-shaped bearing material supporting the rotary shaft on an inner side of the back-spring, the foil gas bearing comprises an electromagnet actuator capable of moving to a radial direction guided by a guide member arranged in the bearing housing in a radial direction and having an adjusting piece supporting an outer peripheral supporting portion of the back-spring and an electromagnet making the adjusting piece moved by supply and stoppage of the magnetic force, and a magnet controlling unit controlling supply and stoppage of magnetic force of the electromagnet actuator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for bearings of small gas turbines, compressors, etc., and supports a back spring made of a thin plate stretched in an annular shape on the inner surface side of a bearing housing, and the circumference of a rotary shaft. The present invention relates to the structure and material of a foil gas bearing in which a plurality of thin plate-shaped bearing members that are provided along the direction and that support the rotating shaft are supported inside the back spring.

[0002]

Foil gas bearings have been used as gas bearings for small gas turbines, compressors and the like. FIG. 10 shows an example of the foil gas bearing (USP41
(See No. 95395) is a cross-sectional view perpendicular to the axis of rotation, in which 20 is a rotary shaft and 02 is a bearing body that supports the rotary shaft 20. The bearing body 02 has a cylindrical bearing housing 03 on the outer side, and a support ring 04 is fitted on the inner side of the bearing housing 03. A plurality of slots 05 are provided on the inner circumference of the support ring 04 along the circumferential direction. Reference numeral 06 denotes a plate-shaped top foil, and its base end is attached to the slot 05 with its tip directed in the rotation direction of the rotary shaft 20. Reference numeral 07 denotes a back spring, the base end of which is fixed to the slot 05 to support the top foils 06 from the outside.

Further, in the conventional foil gas bearing, since the rotary shaft 20 and the top foil (bearing material) 06 come into contact with each other when the equipment equipped with the foil gas bearing starts and stops, the frictional force is small and the surface is small. Since a sliding surface free from damage is required, the surface of the rotary shaft 20 is plated with chrome, and the surface of the top foil 06 is formed with a fired film containing a fluororesin as a main component.

[0004]

In such a foil gas bearing, since the rotating shaft 20 and the top foil 06 come into contact with each other when the equipment equipped with the foil gas bearing starts and stops, the frictional force due to the contact is suppressed. Requires that. However, in the conventional foil gas bearing shown in FIG. 10, when the length of the top foil 06 is increased to reduce and suppress the frictional force, the back spring 07 having a long leg length is used accordingly. That is, the rigidity of the back spring 07 is lowered, and the back spring 07 is easily broken.

A foil gas bearing (hereinafter referred to as a comparative example) shown in FIG. 9 has been proposed as a solution to this problem. In FIG. 9, 1 is a bearing housing,
Reference numeral 20 is a rotary shaft, 2 is a top foil provided along the outer periphery of the rotary shaft 20, and 3 is a back spring provided between the top foil 2 and the bearing housing 1 to support the top foil 2. .

A plurality of recesses 3c are formed along the circumferential direction of the back spring 3, and the back spring 3 is formed.
Is fixed in the groove 5 of the bearing housing 1 such that a portion between the concave portion 3c forming portions has a gap with respect to the inner circumference of the bearing housing 1. Then, the top foil 2 is divided into a plurality of pieces along the circumferential direction, a convex portion 53 is formed at the base of each top foil 2, and the convex portion 53 has a margin in the concave portion 3c of the back spring 3. Are in sliding contact with each other.

However, in such a comparative example,
When the protrusion 53 formed on the base of each top foil 2 is fitted into the recess 3c of the back spring 3 in an unstable mounting state, the accurate dimension between each top foil 2 and the back spring 3 is not measured. It cannot be controlled, and the back spring 3 rises and it becomes difficult to maintain the bearing clearance between each top foil 2 and the rotary shaft 20 at a required value. Further, when the top foils 2 and the back springs 3 are assembled, the bearing clearances are uniquely set by fitting the convex portions 53 into the concave portions 3c. It cannot be done during operation if necessary.

Further, in the foil gas bearing of the comparative example, since the frictional force when the rotating shaft 20 and the top foil 2 come into contact with each other at the time of starting and stopping the equipment is suppressed, the rotating shaft 20 is prevented.
The surface of the top foil 2 is chromium-plated, and the surface of the top foil 2 is formed with a fired film containing a fluororesin as a main component. The fired film of the fluororesin has a maximum operating temperature of about 200 ° C. and heat resistance. Is low, the working gas temperature is 600
It is difficult to apply it to high temperature parts such as gas turbines that reach around ℃.

In view of the problems of the prior art, the present invention provides a rotating shaft and a bearing material (top foil) at the time of starting and stopping the equipment.
The frictional force due to contact with the back spring can be suppressed, and the back spring can be easily and accurately mounted on the bearing housing, so that the bearing clearance between the rotary shaft and the bearing material can be accurately maintained and the bearing clearance can be maintained. It is possible to provide a foil gas bearing that can be adjusted in the assembled state and during operation, and by increasing the maximum operating temperature of the bearing material to improve heat resistance, which can be applied to high temperature members such as gas turbines without any trouble. To aim.

[0010]

In order to solve the above problems, the present invention provides a thin plate stretched in an annular shape on the inner surface side of a bearing housing along the circumferential direction of the inner surface of the bearing housing. A foil gas bearing that supports a back spring made of, and that supports a plurality of thin plate-shaped bearing members that are provided along the circumferential direction of the rotary shaft and axially supports the rotary shaft inside the back spring, The bearing housing includes a guide member including a slide groove provided in a radial direction, and a mating portion which is guided by the guide member and is movable in the radial direction and in which ends of the back spring are engaged with each other. An electromagnet actuator having an adjusting piece for supporting the outer peripheral support portion of the back spring and an electromagnet connected to the adjusting piece to move or settle the adjusting piece by cutting off the magnetic force. An inner diameter of the back spring via the outer peripheral support portion by moving the adjusting piece of the electromagnet actuator along the guide member. We propose a foil gas bearing which is characterized in that its dimensions are adjustable.

According to a second aspect of the present invention, a back spring, which is a thin plate stretched in an annular shape along the circumferential direction of the inner surface of the bearing housing, is supported on the inner surface side of the bearing housing, and the back spring is provided along the circumferential direction of the rotary shaft. A plurality of thin plate-shaped bearing members that support the rotary shaft and are supported inside the back spring, a guide member including a slide groove radially provided in the bearing housing. And an adjusting piece for supporting the outer peripheral support portion of the back spring, which is guided by the guide member, is movable in the radial direction, and includes a mating portion in which the ends of the back spring are engaged with each other. A fluid pressure actuator that moves or stabilizes the adjustment piece by supplying or disconnecting the pressure fluid, and a pressurized fluid control device that controls the supply or disconnection of the pressurized fluid to the fluid pressure actuator are provided. , Characterized in that the adjusting piece of the hydraulic actuator and configured to adjust the inner diameter of the back spring through the periphery supporting member by moving along the guide member.

[0012] In the first and second aspects, preferably, as in the third aspect, the outer peripheral support portion of the back spring is formed at the end portion of the adjustment piece so as to be able to contact the tapered surface. Further, preferably, as in claim 4, either the electromagnet actuator or the fluid pressure actuator and the outer peripheral support portion are provided at a plurality of positions along the circumferential direction.

According to the first to fourth aspects of the present invention, low rotation including a fixed time after the start of the equipment equipped with the foil gas bearing or a start until the rotation speed of the rotary shaft rises to the constant rotation speed. During operation, by applying magnetic force to the electromagnet of the electromagnet actuator by the magnet control device according to claim 1, or by supplying or discharging the pressurized fluid of the fluid pressure actuator by the pressurized fluid control device according to claim 2. , The adjustment piece that supports the outer peripheral support portion of the back spring is moved in the radial direction.

By the radial movement of the adjusting piece, the back spring and the bearing material supported inside the back spring are expanded in the radial direction by the elastic force of the back spring, and the bearing clearance between the rotary shaft and the bearing material is increased. Is expanded. As a result, the contact between the rotating shaft and the bearing material is avoided or becomes a slight contact state during the low rotation operation of the device, the frictional force due to the contact is suppressed, and the starting torque is reduced at the time of starting.

When a certain period of time has elapsed after the start-up as described above, or the number of rotations of the rotating shaft reaches a certain number of revolutions and the rotating shaft levitates due to such an increase in the number of rotations, the magnet controller controls the electromagnet actuator. The magnetic force of the electromagnet is shut off, or the pressurizing fluid of the fluid pressure actuator is operated by the pressurizing fluid control device in the opposite manner to the above to move the adjusting piece toward the center. As a result, the bearing clearance is reduced, and the rotary shaft is supported by the gas bearing including the bearing material in a state where the vibration is small, and operates smoothly.

Therefore, according to this invention, the magnet control device of the first aspect controls the magnetic force of the electromagnet actuator, or the pressurized fluid control device of the second aspect controls the supply and discharge of the pressurized fluid of the fluid pressure actuator. Thus, the adjustment piece supporting the outer peripheral support portion of the back spring can be moved on the radial line to freely adjust the bearing clearance. As a result, the bearing clearance can be easily adjusted from the outside even during operation without removing the bearings at all in the assembled state, and the frictional force at the time of low rotation including the start-up is suppressed, and the start-up at the start-up is suppressed. It is possible to obtain a gas bearing that can reduce the torque and can support the rotating shaft in a state of small vibration at high rotation.

According to the third aspect of the invention, the back spring can be positioned accurately by bringing the outer peripheral support portion of the back spring into contact with the tapered surface provided at the end of the adjusting piece, and the back clearance can be accurately positioned. The adjustment is further simplified and the adjustment accuracy is improved.

The invention described in claims 5 to 8 is defined by claim 1.
The invention of claim 5 relates to the invention of the material of the foil gas bearing having the constitutions 4 to 4, wherein the outer peripheral surface of the rotating shaft is coated with hard carbon, and a fluororesin firing film is formed on the surface of the bearing material. It is characterized by Claim 5
According to the described invention, the hard carbon film is a hard film having solid lubricity as compared with the chrome plating or the ceramic film, and thus is suitable for surface coating of the bearing surface, and the surface of the rotary shaft is coated with the hard carbon film. By combining with a bearing material having a fluororesin baked film formed thereon, the transition film lubrication effect is exerted, wear resistance is improved, and the bearing life can be extended.

According to a sixth aspect of the invention, graphite is used as the bearing material.
Or molybdenum disulfide (MoS _Two) Or graphite and
And molybdenum disulfide (MoS_Two) Any one of
It is characterized by being coated with a film. Claim 7
The invention described is an acid containing two or more kinds of metals in the bearing material.
Characterized by being coated with a film made of a compound
It In the invention according to claim 8, the bearing material includes graphite and two kinds.
Coated with a film made of oxide containing more than one metal
It is characterized by

According to the invention of claims 6 to 8, the bearing material is either graphite or molybdenum disulfide (MoS ₂ ) or graphite and molybdenum disulfide (MoS ₂ ).
600 ° C. by coating a film composed of two kinds, a film composed of an oxide containing two or more kinds of metals, or a film composed of an oxide containing graphite and two or more kinds of metals, respectively.
The coefficient of friction and the amount of wear can be kept as low as normal temperature up to a high temperature. As a result, the coefficient of friction between the bearing material and the rotating shaft can be maintained at a low coefficient of friction in a wide temperature range from room temperature to a high temperature of about 600 ° C. Even during the contact operation between the material and the rotating shaft, there is no increase in the amount of wear on the bearing surface between the bearing material and the rotating shaft in a wide temperature range from room temperature to a high temperature of about 600 ° C. The maximum operating temperature can be increased, and it can be applied to high-temperature members such as gas turbines where the ambient temperature of the bearing becomes high without any problems.

According to a ninth aspect of the invention, a back spring made of a thin plate stretched in an annular shape along the circumferential direction of the inner surface of the bearing housing is supported on the inner surface side of the bearing housing, and the back spring is provided along the circumferential direction of the rotary shaft. A plurality of thin plate-shaped bearing members that support the rotary shaft are supported inside the back spring, in the vicinity of the journal portion of the rotary shaft supported by the bearing members. A magnet control device that controls the supply and disconnection of magnetic force to the electromagnet provided and also energizes the electromagnet for a set fixed period to levitate the journal part and form a minute gap between the bearing part and the bearing material. It is characterized by having and.

According to the invention, the magnet control device is operated during a low speed operation including a fixed time after the equipment equipped with the foil gas bearing is started or a startup time until the rotation speed of the rotary shaft rises to the constant rotation speed. Magnetic force is applied to the electromagnet by the repulsive force between the electromagnet and the journal portion of the rotating shaft, which causes the journal portion to float and a minute gap to be formed between the journal member and the bearing material. This minute gap can be adjusted by changing the magnetic force of the electromagnet by the magnet control device. Due to the floating of the journal section,
The bearing clearance between the journal portion and the bearing material forming the bearing is enlarged. As a result, the contact between the rotating shaft and the bearing material is avoided or becomes a slight contact state during the low rotation operation of the device, the frictional force due to the contact is suppressed, and the starting torque is reduced at the time of starting.

When a certain period of time has elapsed after the start-up as described above, or the number of rotations of the rotating shaft reaches a certain number of revolutions and the rotating shaft levitates due to the increase in the number of rotations, the magnet control device causes the magnetic force of the electromagnet to be increased. Is cut off to remove the repulsive force between the electromagnet and the journal portion of the rotary shaft. As a result, the bearing floats with the bearing clearance reduced due to the rotation of the rotating shaft, and the rotating shaft is supported by the gas bearing containing the bearing material in a state of small vibration, and operates smoothly.

According to this invention, therefore, the repulsive force between the electromagnet and the journal of the rotary shaft can be adjusted by controlling the magnetic force of the electromagnet by the magnet control device, and the bearing clearance can be adjusted freely. As a result, the bearing clearance can be easily adjusted from the outside even in the assembled state and during operation without removing the bearings at all, and the frictional force at low rotation including start-up is suppressed to reduce the start-up torque at start-up. It is possible to obtain a gas bearing that can reduce the number of vibrations and can support the rotating shaft in a state of low vibration at high rotation.

According to a tenth aspect of the present invention, a back spring made of a thin plate stretched in an annular shape is supported on the inner surface side of the bearing housing along the circumferential direction of the inner surface, and the back spring is supported along the circumferential direction of the rotary shaft. In a foil gas bearing having a plurality of thin plate-shaped bearing members that support the rotating shaft supported inside the back spring, a portion close to the journal portion of the rotating shaft supported by the bearing member. Further, a cooling fan for supplying cooling air is fixed to a bearing portion including the bearing material.

According to this invention, the bearing can be cooled by flowing the air sucked in from the outside of the rotary shaft in the axial direction by the cooling fan provided on the outer periphery of the rotary shaft, so that the bearing is specially forced like the conventional one. A cooling means is not required, and the bearing can be maintained at an appropriate temperature with a very simple means.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto, unless there is a specific description, and are merely illustrative examples. Nothing more.

FIG. 1 shows a first embodiment of a foil gas bearing structure according to the present invention. (A) is a front view as seen in a direction perpendicular to the rotation axis (rotation axis is omitted) (B) is a mating portion. It is an AA arrow line view in (A) which shows details. FIG. 2 is a magnet control block diagram in the first embodiment. FIG. 3 is a view corresponding to FIG. 1A showing the second embodiment. FIG. 4 is a pneumatic pressure control block diagram in the second embodiment. FIG. 5 is a schematic cross-sectional configuration diagram taken along the axis of the foil gas bearing portion according to the third embodiment. FIG. 6 is a schematic cross-sectional configuration diagram taken along the axis of the foil gas bearing portion according to the fourth embodiment. FIG. 7 is a table showing a first embodiment of materials for foil gas bearings. FIG. 8 is a table showing a second embodiment of the material for foil gas bearings.
FIG. 9 is a front view showing a comparative example as viewed in a direction perpendicular to the axis of rotation.

In FIG. 1 showing a first embodiment of the foil gas bearing structure, 1 is a cylindrical bearing housing, 100 is a rotary shaft center of a rotary shaft 20 (see FIG. 9) (not shown), and 2 is a rotary shaft center. A plurality of (three in this example) thin foils are provided along the outer circumference of the rotary shaft 20 to form a bearing material, and the top foils 3 are provided between the top foil 2 and the bearing housing 1. The back spring is a thin plate that supports the top foil 2.

The back spring 3 is annularly stretched along the circumferential direction of the inner ring 15 fixedly mounted on the inner circumference of the bearing housing 1 and has a fitting portion whose end portion is fitted to one position on the circumference. 4 is provided. The mating portion 4 is installed inside a groove 5 provided in an adjusting piece 11 which will be described later.
As shown in FIG. 3, between the two outer mating parts 42 projecting on one side of both ends of the back spring 3, an inner mating part 41 projecting on the other side of the both ends is provided. Cross in a form in which tension is applied to. The relative movement in the width direction of the mating portion 4 is regulated by bringing the locking surfaces 43 formed on the outer mating portion 42 and the inner mating portion 41 into contact with each other.

Reference numeral 030 is an electromagnet actuator, which is an adjusting piece 11 fitted in the slide groove 10 so as to be movable in the radial direction, and is attached to the outer surface of the bearing housing 1 to apply a magnetic force to the adjusting piece 11 to move. Alternatively, it is composed of an electromagnet 23 for allowing it to settle, a spring for returning the adjusting piece 11, and the like. The electromagnet 23 is fitted and inserted into a rod portion 011 provided at one end of the adjusting piece 11, and the adjusting piece 11 is inserted into the fitting hole 020a of the electromagnet 23 by cutting magnetic force to the electromagnet 23. It is designed to move back and forth. The electromagnet actuators 030 are provided in plural sets in the circumferential direction of the back spring 3 (three sets at equal intervals in the circumferential direction in this example).

A groove 5 is provided in a radial direction on one end side of the adjusting piece 11, and tapered surfaces 14 are formed on both sides of the groove 5.
Are formed. The outer surface of the back spring 3 contacts the tapered surface 14, and the outer periphery of the connecting portion between the mating portion 4 and the annular portion of the back spring 3 contacts the tapered surface 6. By doing so, the back spring 3 is positioned. Again 0
Reference numeral 6 denotes a convex portion that partially protrudes from the back spring 3, and is a groove 5 of the adjusting piece 11 other than the installation portion of the mating portion 4.
It is possible to contact the tapered surface 6 corresponding to. The plurality of (three in this example) top foils 2 are supported at the inside of the back spring 3 by bending their bases along the respective tapered surfaces 6.

Reference numeral 30 denotes a magnet control device, which is a control line 22.
It is connected to each of the electromagnet actuators 030 via the, and controls the supply and disconnection of the magnetic force of the electromagnet actuators 030. Details of the magnet control device 30 will be described later.

Next, the operation of the foil gas bearing having the above structure will be described. In FIG. 2, reference numeral 33 denotes a timer, which keeps the bearing clearance between the rotary shaft 20 of the foil gas bearing and the top foil 2 larger than a certain value from the start of equipment equipped with the foil gas bearing. The time required to reduce the frictional resistance, that is, the low rotation time is set. Reference numeral 34 is a rotation detector for detecting the number of revolutions (the number of revolutions per minute) of the rotary shaft 20.

Reference numeral 32 is a magnet operation judging section, which is the timer 3
3, the low rotation time and the rotation speed of the rotary shaft 20 are input from the rotation detector 34. In the magnet operation determination unit 32, it is possible that the set time from the timer 33 is within the low rotation time or the rotation speed of the rotary shaft 20 from the rotation detector 34 keeps the bearing clearance larger than a certain value. When any of the required rotational speeds is equal to or lower than the required rotational speed, the operation command signal of the electromagnet actuator 030 is output to the magnet operation control unit 31.

In the magnet operation control section 31, the electromagnet actuator 03 is operated while the magnet operation determination section 32 issues an operation command for the electromagnet actuator 030.
A magnetic force is applied to the electromagnet 23 of 0. Due to the magnetic force of the electromagnet 23, the adjusting piece 11 is pulled outward in the radial direction against the spring force of the spring 21. The taper surface 14 of the adjusting piece 11 and the back spring 3 in contact with the taper surface 14 are adjusted in circumferential length by changing the crossing length of the outer mating portion 42 and the inner mating portion 41 of the mating portion 4. Since it is possible, the back spring 3 moves outward in the radial direction according to the movement of the adjusting piece 11,
The diameter of the top foil 2 is expanded together with the back spring 3, and the gap between the top foil 2 and the rotary shaft 20, that is, the bearing clearance is expanded.

Therefore, during a low rotation operation including a fixed time after the equipment equipped with the foil gas bearing is started, that is, the low rotation time set in the timer 33, or the startup until the rotation speed reaches the limit rotation speed, Magnet control device 3
A magnetic force is applied to the electromagnet 23 of the electromagnet actuator 030 by 0 to move the adjustment piece 11 supporting the outer peripheral support portion of the back spring 3 radially outward to expand the bearing clearance, thereby reducing the rotation speed of the device. During operation, contact between the rotary shaft 20 and the top foil 2, which is a bearing material, is avoided or a slight contact state is established, and the frictional force due to the contact is suppressed, and the starting torque is reduced during startup.

Also, by bringing the outer peripheral support portion of the back spring 3 into contact with the tapered surface 14 provided at the end of the adjusting piece 11, the back spring 3 can be accurately positioned and the bearing clearance can be adjusted. Further simplification and adjustment accuracy are improved.

When the rotating shaft 20 levitates due to an increase in the number of revolutions after a certain period of time has passed after the start-up as described above, the magnet control device 30 causes the electromagnet actuator 030.
The magnetic force of the electromagnet 23 is cut off. As a result, the adjusting piece 11 is pushed back inward in the radial direction by the spring force of the spring 21, and the back spring 3 and the top foil 2 are
And the bearing clearance is reduced, and the rotary shaft 20 is supported by the gas bearing including the top foil 2 in a state of small vibration, and operates smoothly. In addition, in the first embodiment, one of the timer 33 and the rotation detector 34 may be provided and the other may be omitted.

In the second embodiment of the foil gas bearing structure shown in FIGS. 3 and 4, instead of the electromagnet actuator 030 and the magnet control device 30 in the first embodiment, a pneumatic actuator 050 and an air supply control device 50 are used. It is provided.

That is, in FIGS. 3 and 4, reference numeral 050 denotes a pneumatic actuator, which is an adjusting piece 53 fitted in the slide groove 10 provided in the bearing housing 1 so as to be movable in the radial direction, and an upper surface of the adjusting piece 53. Air chamber 55 formed so that the adjustment piece 53 is returned, and a spring 54 for returning the adjustment piece 53.
Etc. The pneumatic actuators 050 are provided in plural sets in the circumferential direction of the back spring 3 (three sets at equal intervals in the circumferential direction in this example).

A groove 5 is provided in a radial direction at one end of the adjusting piece 53, and tapered surfaces 43 are provided on both sides of the groove 5.
Are formed. The outer surface of the back spring 3 contacts the tapered surface 43, and the outer periphery of the connecting portion between the mating portion 4 and the annular portion of the back spring 3 contacts the tapered surface 43. By doing so, the back spring 3 is positioned. 56
Is an O-ring for sealing fitted on the outer periphery of the adjusting piece 53.

Reference numeral 50 denotes an air supply control device, which is an air pipe 4
The air pressure actuator 050 is connected to each of the air pressure actuators 050 through 5 to control the supply and disconnection of the pressurized air of each of the air pressure actuators 050. Details of the air supply control device 50 will be described later. The other structure is the same as that of the first embodiment, and the same members as these are denoted by the same reference numerals.

The operation of the second embodiment will be described. In FIG. 4, 33 and 34 are the same timers and rotation detectors as in the first embodiment. Reference numeral 52 denotes an actuator operation determination unit, which inputs the low rotation time from the timer 33 and the rotation speed of the rotary shaft 20 from the rotation detector 34. In the actuator operation determination section 52,
Either within the low rotation time set in the timer 33, or below the limit rotation speed at which the rotation speed of the rotation shaft 20 from the rotation detector 34 is required to keep the bearing clearance larger than a certain value. In this case, the operation command signal for the pneumatic actuator 050 is not transmitted. And
In the actuator operation determination unit 52, it is determined that the low rotation time from the timer 33 is reached or the rotation speed of the rotation shaft 20 from the rotation detector 34 keeps the bearing clearance larger than a certain value. When either one of the required rotation speeds is reached, the actuator control unit 5 outputs an operation command signal for the pneumatic actuator 050.
Output to 1.

Within the low rotation time from the timer 33 or below the limit rotation speed, the actuator control section 51 causes the pneumatic actuator 0
The supply of the pressurized air to the air chamber 55 of 50 is shut off. By shutting off the pressurized air, the adjusting piece 53 is pulled outward in the radial direction by the spring force of the spring 54.
As a result, the tapered surface 43 of the adjusting piece 53 and the back spring 3 that is in contact with the tapered surface 43 move outward in the radial direction, and the diameter of the top foil 2 is expanded together with the back spring 3, and the top foil 2 and the rotary shaft are rotated. The gap with 20, that is, the bearing clearance is enlarged.

Therefore, at the time of low rotation operation including the fixed time after the start of the equipment equipped with the foil gas bearing, that is, the low rotation time set in the timer 33, or at the time of low rotation operation including start-up until the limit rotation speed is reached, The adjusting piece 5 that shuts off the air supply to the air chamber 55 by the air supply control device 50 and supports the outer peripheral support portion of the back spring 3.
3 is moved to the outside in the radial direction to expand the bearing clearance, so that the rotating shaft 20 can be operated during low-speed operation of the device.
The contact between the bearing and the top foil 2 which is the bearing material is avoided, or a slight contact state is established to suppress the frictional force due to the contact, and the starting torque is reduced at the time of starting.

On the other hand, the actuator operation judging section 52
During the period when the operation command of the pneumatic actuator 050 is issued from the above, the actuator control unit 51 supplies the pressurized air to the air chamber 55 of the pneumatic actuator 050 through the air pipe 45. Such an air tube 4
By the supply of the pressurized air into the inside 5, the adjusting piece 53 is pulled back inward in the radial direction against the spring force of the spring 54. As a result, the tapered surface 43 of the adjusting piece 53 and the back spring 3 that is in contact with the tapered surface 43 move inward in the radial direction, the diameter of the top foil 2 is reduced together with the back spring 3, and the top foil 2 and the rotary shaft are rotated. The gap with 20, that is, the bearing clearance is reduced.

Therefore, when the rotating shaft 20 floats due to an increase in the number of revolutions after a certain period of time has passed after the start-up as described above, the adjusting piece 53 is radially moved by the supply of the pressurized air to the air chamber 55. By being pushed back inward, the diameters of the back spring 3 and the top foil 2 are reduced, and the bearing clearance is reduced, so that the rotating shaft 20 is supported by the gas bearing including the top foil 2 in a state of small vibration, and is smoothly supported. Be driven to.

In the third embodiment shown in FIG. 5, reference numeral 20 denotes a rotary shaft, both ends of which are rotatably supported by the bearing housing 1 via bearings 001 (100 is a rotary shaft center).
The bearing 001 is composed of a foil gas bearing similar to that of the first and second embodiments. Reference numeral 61 denotes an electromagnet, which is provided on a side portion of each bearing housing 1 in proximity to the journal portion 021 of the rotary shaft 20. Reference numeral 60 denotes a magnet control device, which has the same structure as the magnet control device 30 in the first embodiment, and is connected to the electromagnet 61 by a control line 62.

In the third embodiment, at the time of starting the equipment equipped with the foil gas bearing and during a certain period of time after the start or during low rotation operation until the number of rotations of the rotary shaft 20 rises to a certain number of rotations, As with the first embodiment, the electromagnet 61 is controlled by the magnet operation control unit 31 of the magnet control device 60.
The same magnetic force is applied to. Due to the magnetic force, a repulsive force is generated between the electromagnet 61 and the journal portion 021 of the rotary shaft 20, the journal portion 021 is floated, and a minute gap c, that is, a bearing clearance is formed between the journal portion 021 and the bearing 001. It The minute clearance c (bearing clearance) can be adjusted to a required bearing clearance by changing the magnetic force of the electromagnet 61 by the magnet control device 60.

By forming the bearing clearance (c) between the journal portion 021 and the bearing 001 by the floating of the journal portion 021, contact between the rotary shaft 20 and the bearing 001 is avoided during the low rotation operation of the equipment. The frictional force due to the contact is suppressed. As a result, the starting torque at the time of starting is reduced.

When a certain time has elapsed after the start-up as described above and the rotating shaft 20 floats due to an increase in the number of rotations, the magnet control device 60 shuts off the magnetic force of the electromagnet 61. As a result, the levitation force of the journal portion 021 is released and the rotary shaft 20 floats due to its own rotation, and the bearing clearance is reduced as compared to during the low rotation operation.
Is the bearing 0 in the form of a gas bearing in a state of small vibration.
It is supported by 01 and operates smoothly.

In the fourth embodiment shown in FIG. 6, the cooling fan 70 is fixed to a portion of the rotary shaft 20 near the journal portion 021. The cooling fan 70 is of a flow type in which a plurality of blades 73 are fixed to the outer circumference of an annular boss portion 72 fixed to the outer circumference of the rotary shaft 20 at equal intervals along the circumferential direction. I am a fan. Although FIG. 6 shows only one bearing portion, the cooling fan 70 is provided on both bearing portions.

In the fourth embodiment, the rotary shaft 2
When 0 rotates, the air sucked from the outside of the rotating shaft 20 is pressed by the blades by the vane-type cooling fan 70 provided on the outer periphery of the rotating shaft 20 like a Z arrow to rotate the shaft of the rotating shaft 20. It is possible to cool the bearing 001 by flowing it in the direction. Therefore, unlike the conventional one, a special forced cooling means is not required, and the blow-type cooling fan 70 is provided on the outer periphery of the rotary shaft 20, which is extremely simple. The bearing can be maintained at an appropriate temperature by any means.

Next, in the present invention, the material of the foil gas bearing shown in FIGS. 1 and 3 is constructed as follows. That is, in the first embodiment of the material for the foil gas bearing, as shown in FIG. 7, the outer peripheral surface of the rotary shaft 20 is coated with hard carbon to form the top foil 2
A fluororesin baked film is formed on the surface of (bearing material). Figure 7
Is the result of a comparative experiment of the material for foil gas bearings according to the first embodiment. In the figure, reference numeral 1 is a conventional material (comparative material) in which the outer peripheral surface of the rotary shaft 20 is coated with chrome. In each case, the surface of the top foil 2 (bearing material) is coated with a hard carbon, and a fluororesin firing film (PTFE firing film) is formed on the surface thereof.

As is apparent from the figure, the material 2 of the present invention is a conventional material (comparative material) at both room temperature (room temperature) and high temperature (200 ° C.).
The friction coefficient and the amount of wear are reduced compared to That is,
According to this embodiment, the hard carbon film of the material of the present invention is a hard film having solid lubricity as compared with the conventional material (comparative material) such as chrome plating or ceramic film.
The surface film is coated with a top foil 2 (bearing material) having a fluororesin baked film formed on the surface thereof, so that the transition film lubrication effect is exhibited and the wear resistance is improved.

Next, in the second embodiment of the material for foil gas bearing, the surface of the top foil 2 (bearing material) is coated with the materials shown in Nos. 4 to 14 in the table of FIG. The rotary shaft 20 is not surface-treated. That is, FIG. 8 shows the results of a comparative experiment of the material for foil gas bearings according to the second embodiment. In the drawing, 1 to 3 and 15 are conventional materials (comparative material) for surface coating of the top foil 2 (bearing material), 4 Nos. 14 to 14 are materials of the present invention.

In FIG. 8, the first material of the material of the present invention is
On the top foil 2, molybdenum disulfide (Mo
A film made of S ₂ ) (material of the invention 4), a film made of graphite (material 5 of the invention), or a film made of graphite and molybdenum disulfide (MoS ₂ ) (material 6 of the invention) is coated. The second material of the material of the present invention is, on the top foil 2, a film made of potassium tungstate (K ₂ WO ₄ ) (material of the present invention 7) or a film made of sodium tungstate (Na ₂ WO ₄ ). Inventive material 8), a film made of potassium molybdenum (K ₂ MoO ₄ ) (inventive material 9), or sodium molybdenum (N)
The film (inventive material 10) made of a ₂ MoO ₄ ) is coated. The third material of the material of the present invention is that the top foil 2 has graphite and potassium tungstate (K ₂ W).
O ₄ ) film (invention material 11), graphite and sodium tungstate (Na ₂ WO ₄ ) film (invention material 12), or graphite and potassium molybdenum (K ₂ MoO ₄ ). (Inventive material 13), or graphite and sodium molybdenum (Na ₂ MoO
₄ ) is coated (the present invention material 14).

As is apparent from FIG. 8, the first of the present invention materials
The third material (materials of Nos. 4 to 14) has a reduced friction coefficient and wear amount compared with the conventional material (comparative material) at both normal temperature (room temperature) and high temperature (200 ° C, 400 ° C, 600 ° C), In particular, even at a high temperature of 600 ° C., the friction coefficient and the wear amount are almost the same as those at room temperature (room temperature) and are low.

During operation of equipment equipped with a foil gas bearing having such a configuration, at the time of low rotation operation including start-up and before stoppage of the equipment, operation is performed with the rotating shaft 20 and the top foil 2 in contact with each other. However, according to the second embodiment of the material for foil gas bearing, the friction coefficient and the wear amount can be kept as low as normal temperature up to a high temperature of about 600 ° C. It is possible to maintain the friction coefficient and the amount of wear between the rotating shaft 20 and the rotary shaft 20 at low values in a wide temperature range from normal temperature to high temperature of about 600 ° C. As a result, even in the contact operation between the bearing material and the rotating shaft such as in the low rotation operation, the bearing surfaces of the top foil 2 and the rotating shaft 20 in a wide temperature range from room temperature to a high temperature of about 600 ° C. It is possible to raise the maximum operating temperature of the top foil 2 (bearing material) without any noticeable increase in wear, and it can be applied to high temperature members such as gas turbines where the ambient temperature of the bearing becomes high without any trouble.

[0061]

As described above, according to the inventions of claims 1 to 4, the magnetic force of the electromagnet actuator is controlled by the magnet control device of claim 1, or the fluid is controlled by the pressurized fluid control device of claim 2. By controlling the supply and discharge of the pressurized fluid of the pressure actuator, the adjustment piece that supports the outer peripheral support portion of the back spring can be moved along the radial line to freely adjust the bearing clearance. As a result, the bearing clearance can be easily adjusted from the outside even during operation without removing the bearings at all in the assembled state, and the frictional force at the time of low rotation including the start-up is suppressed, and the start-up at the start-up is suppressed. It is possible to obtain a gas bearing that can reduce the torque and can support the rotating shaft in a state of small vibration at high rotation.

According to the third aspect of the invention, the back spring can be accurately positioned by bringing the outer peripheral support portion of the back spring into contact with the tapered surface provided at the end of the adjustment piece, and the bearing clearance can be increased. The adjustment is further simplified and the adjustment accuracy is improved.

According to a fifth aspect of the present invention, there is provided a bearing material, wherein a hard carbon film having solid lubricity and suitable for surface coating is coated on the surface of the rotary shaft, and a fluororesin firing film is formed on the surface. By combining them, the transition film lubrication effect is exerted, the wear resistance is improved, and the bearing life is extended.

Further, according to the invention of claims 6 to 8, graphite or molybdenum disulfide (Mo) is used as the bearing material.
S ₂ ) or graphite and molybdenum disulfide (MoS ₂ )
To a high temperature of about 600 ° C. by coating a film made of any one of the above, a film made of an oxide containing two or more kinds of metals, or a film made of an oxide containing graphite and two or more kinds of metals, respectively. The friction coefficient and the amount of wear can be kept as low as at room temperature.

As a result, the coefficient of friction between the bearing material and the rotary shaft can be maintained at a low coefficient of friction and wear in a wide temperature range from room temperature to a high temperature of about 600 ° C.
Even during contact operation between the bearing material and the rotating shaft, such as during start-up or low rotation, wear on the bearing surface between the bearing material and the rotating shaft increases over a wide temperature range from room temperature to a high temperature of about 600 ° C. It is possible to raise the maximum operating temperature of the bearing material without seeing, and it can be applied to high temperature members such as gas turbines where the ambient temperature of the bearing becomes high without any trouble.

According to the ninth aspect of the invention, the repulsive force between the electromagnet and the journal portion of the rotary shaft is adjusted by controlling the magnetic force of the electromagnet by the magnet control device, and the bearing clearance can be adjusted freely. it can. As a result, the bearing clearance can be easily adjusted from the outside without removing the bearings and in the assembled state and during operation.
It is possible to obtain the gas bearing that can suppress the frictional force at the time of low rotation including the time of starting to reduce the starting torque at the time of starting and can support the rotating shaft in the state of small vibration at the time of high rotation.

According to the tenth aspect of the present invention, the bearing can be cooled by flowing the air sucked from the outside of the rotating shaft in the axial direction by the cooling fan provided on the outer periphery of the rotating shaft, which makes it possible to cool the bearing. Thus, no special forced cooling means is required, and the bearing can be maintained at an appropriate temperature with a very simple means.

[Brief description of drawings]

FIG. 1 shows a first embodiment of a foil gas bearing structure according to the present invention, (A) is a front view seen in a direction perpendicular to a rotation axis (rotation axis is omitted), and (B) is a detail of a mating portion. Show (A)
FIG. 9 is a view on arrow AA in FIG.

FIG. 2 is a magnet control block diagram in the first embodiment.

FIG. 3 is a view corresponding to FIG. 1A showing a second embodiment.

FIG. 4 is a block diagram of pneumatic control in the second embodiment.

FIG. 5 is a schematic cross-sectional configuration diagram taken along an axis of a foil gas bearing portion according to a third embodiment.

FIG. 6 is a schematic cross-sectional configuration diagram along a shaft center line of a foil gas bearing portion according to a fourth embodiment.

FIG. 7 is a table showing a first embodiment of materials for foil gas bearings.

FIG. 8 is a table showing a second example of the material for foil gas bearings.

FIG. 9 is a front view showing a comparative example as viewed in a direction perpendicular to the axis of rotation.

FIG. 10 is a diagram corresponding to FIG. 3 showing a conventional technique.

[Explanation of symbols]

1 Bearing housing 001 bearing 2 top foil 3 back spring 4 mating section 5 grooves 14, 43 Tapered surface 10 slide groove 11,53 Adjustment piece 15 Inner ring 20 rotation axis 021 Journal Department 21, 54 spring 30 60 Magnet control device 33 timer 34 rotation detector 41 Inner part 42 Outer mating part 43 Locking surface 50 Air supply controller 050 Pneumatic actuator 55 Air chamber 70 Cooling fan 23, 61 Electromagnet

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Bunji Takahashi             5-717-1, Fukahori-cho, Nagasaki-shi Mitsubishi Heavy Industries             Business Nagasaki Institute (72) Inventor Takero Makino             5-717-1, Fukahori-cho, Nagasaki-shi Mitsubishi Heavy Industries             Business Nagasaki Institute F term (reference) 3J012 AB01 BB01 CB02 CB03 CB04                       DB01 DB04 DB06 EB07 EB08                       EB10 EB11

Claims (10)

[Claims] 1. A back spring made of a thin plate stretched in an annular shape along the circumferential direction of the inner surface of the bearing housing is supported, and a plurality of back springs are provided along the circumferential direction of the rotary shaft. A foil gas bearing in which a thin plate-shaped bearing material that supports a rotary shaft is supported inside the back spring, and a guide member including a slide groove provided in the bearing housing in a radial direction is provided, and the guide is provided. An adjusting piece which is guided by a member and is movable in the radial direction and which supports an outer peripheral supporting portion of the back spring including a mating portion in which ends of the back spring are engaged with each other, and a magnetic force supplied by being connected to the adjusting piece. An electromagnet actuator having an electromagnet that moves or stabilizes the adjustment piece by disconnection;
A magnet control device for controlling the supply and disconnection of the magnetic force of the electromagnet actuator, and adjusting the inner diameter of the back spring via the outer peripheral support portion by moving the adjustment piece of the electromagnet actuator along the guide member. A foil gas bearing characterized by being configured as possible. 2. A back spring made of a thin plate stretched in an annular shape along the circumferential direction of the inner surface of the bearing housing is supported, and a plurality of back springs are provided along the circumferential direction of the rotary shaft. A foil gas bearing in which a thin plate-shaped bearing material that supports a rotary shaft is supported inside the back spring, and a guide member including a slide groove provided in the bearing housing in a radial direction is provided, and the guide is provided. By supplying and disconnecting the pressurized fluid, there is provided an adjusting piece which is guided by a member and is movable in the radial direction, and which supports an outer peripheral support portion of the back spring including a mating portion in which the ends of the back spring are engaged with each other. A fluid pressure actuator for moving or statically adjusting the adjustment piece; and a pressurized fluid control device for controlling the supply and disconnection of the pressurized fluid to the fluid pressure actuator,
A foil gas bearing, wherein an inner diameter of the back spring can be adjusted via the outer peripheral support portion by moving an adjusting piece of the fluid pressure actuator along the guide member. 3. The foil according to claim 1, wherein a taper surface on which an outer peripheral support portion of the back spring can be contacted is formed at an end portion of the adjustment piece. Gas bearing. 4. The foil according to claim 1, wherein either the electromagnet actuator or the fluid pressure actuator and the outer peripheral support portion are provided at a plurality of positions along the circumferential direction. Gas bearing. 5. The foil according to claim 1, wherein the outer peripheral surface of the rotating shaft is coated with hard carbon, and a fluororesin baked film is formed on the surface of the bearing material. Gas bearing. 6. The bearing material is coated with a film made of graphite, molybdenum disulfide (MoS ₂ ) or any one of graphite and molybdenum disulfide (MoS ₂ ). The foil gas bearing according to claim 2. 7. The foil gas bearing according to claim 1, wherein the bearing material is coated with a film made of an oxide containing two or more kinds of metals. 8. The foil gas bearing according to claim 1, wherein the bearing material is coated with a film made of an oxide containing graphite and two or more kinds of metals. 9. A back spring made of a thin plate stretched in an annular shape along the circumferential direction of the inner surface of the bearing housing is supported, and a plurality of back springs are provided along the circumferential direction of the rotary shaft. In a foil gas bearing that supports a thin plate-shaped bearing material that rotatably supports a rotating shaft inside the back spring, an electromagnet provided in proximity to a journal portion of the rotating shaft supported by the bearing material, And a magnet control device for controlling the supply of magnetic force to the electromagnet and energizing the electromagnet for a set fixed period to levitate the journal portion and form a minute gap with the bearing material. Features foil gas bearings. 10. A back spring made of a thin plate stretched in an annular shape along the circumferential direction of the inner surface of the bearing housing is supported, and a plurality of back springs are provided along the circumferential direction of the rotating shaft. In a foil gas bearing formed by supporting a thin plate-shaped bearing material that supports a rotary shaft inside the back spring, the bearing material is provided at a position near the journal portion of the rotary shaft supported by the bearing material. A foil gas bearing characterized in that a cooling fan for supplying cooling air is fixed to a bearing portion including the cooling fan.