JP2005121036A - Gas bearing, bearing device, compressor, and method of controlling behavior of gas bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas bearing capable of satisfactorily supporting a rotating shaft while minimizing a bearing diameter, a bearing device using the gas bearing, a compressor, and a method of controlling the behavior of the gas bearing. <P>SOLUTION: The compressor is formed to support the rotating shaft 3 on a casing through the gas bearing 11 in the state of allowing the rotation about the axis thereof. The gas bearing 11 comprises a bearing body 12 into which the rotating shaft 3 is inserted. A discharge port discharging a working gas in the bearing body 12 to the outside is formed at the upper part of the bearing body 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gas bearing, a bearing device using the gas bearing, a compressor, and an operation control method for the gas bearing.

The gas bearing has a bearing main body through which the rotating shaft is inserted, and a gas layer is formed between the bearing main body and the rotating shaft to reduce the frictional resistance generated between the bearing main body and the rotating shaft. The rotary shaft is supported.
Here, the gas layer is formed over the entire circumference of the rotating shaft by the gas and the surrounding atmosphere supplied from outside the bearing body being wound around the rotating shaft as the rotating shaft rotates.
As such a gas bearing, for example, there is a gas bearing described in Patent Document 1 described later.

Japanese Patent Laid-Open No. 10-318184 (paragraph [0010] and FIG. 1)

However, since the gas bearing performs fluid lubrication with gas, it has a lower load capacity than an oil bearing that performs fluid lubrication with a liquid. In particular, when the rotation speed of the rotation shaft is low, such as when the rotation shaft starts rotating from a stationary state, this tendency becomes more prominent because gas does not easily flow between the rotation shaft and the bearing body.
For this reason, in order to prevent damage to the bearing body even when the rotational speed of the rotating shaft is low, the gas bearing has a load larger than the load capacity required to support the rotating shaft rotating at the rated speed. Ability is required. In order to increase the load capacity, it is necessary to increase the bearing diameter.
That is, the gas bearing becomes larger than an oil bearing having an equivalent load capacity.

  The present invention has been made in view of such circumstances, and is capable of satisfactorily supporting the rotating shaft while minimizing the bearing diameter, a bearing device using the gas bearing, and a compression device. It is an object of the present invention to provide an operation control method for a machine and a gas bearing.

In order to solve the above problems, the gas bearing according to the present invention employs the following means.
That is, the gas bearing according to the present invention is a gas bearing that supports the rotating shaft in the radial direction by forming a gas layer between the rotating shaft and a bearing body through which the rotating shaft is inserted. In the upper part of the bearing body, a discharge port for discharging the gas in the bearing body to the outside is provided.

In the gas bearing configured as described above, the gas in the bearing body is discharged through a discharge port provided at a position above the rotation shaft in the bearing body.
As a result, a pressure difference is generated between the region above and below the rotation shaft in the bearing body (between the vicinity of the discharge port and the other region), and the rotation shaft is sucked up by this pressure difference. (Or pushed up).
In this gas bearing, since the force for lifting the rotating shaft is generated in this way, the surface pressure that the bearing body receives from the rotating shaft is reduced.

  Moreover, the gas bearing according to the present invention is the gas bearing according to claim 1, wherein the inner surface of the bearing body has a protruding portion that protrudes radially inward in the vicinity of the discharge port compared to other regions. It is characterized by being.

The gas bearing configured in this manner has a protruding portion in the vicinity of the discharge port on the inner surface of the bearing body, and the distance from the rotating shaft is narrower than in other regions. The gas flow is restricted at the boundary between the other region and the protrusion.
For this reason, it is possible to reliably generate a differential pressure between a region in the vicinity of the protruding portion in the bearing body and another region (that is, between the region above and below the rotation shaft). Also, with this configuration, the differential pressure generated between the upper region and the lower region of the rotating shaft is increased, and the force for lifting the rotating shaft is increased.

  Moreover, the gas bearing according to the present invention is the gas bearing according to claim 1 or 2, wherein the upper part of the bearing body is configured by an elevating member having the discharge port and movable in the vertical direction. The elevating device for elevating the elevating member is provided in the bearing body.

The gas bearing configured as described above can adjust the size of the space formed between the elevating member and the rotating shaft by elevating the elevating member with the elevating device.
For example, by lowering the elevating member and bringing it close to the rotating shaft, the space formed between the elevating member and the rotating shaft is reduced, so the vicinity of the elevating member and other regions in the bearing body At the boundary, the gas flow is throttled. That is, in the bearing body, the differential pressure generated between the vicinity of the elevating member and the other region is increased, and the force for lifting the rotating shaft is increased.
On the other hand, the space formed between the elevating member and the rotating shaft is increased by raising the elevating member and separating it from the rotating shaft, so that the vicinity of the elevating member and other regions in the bearing body At the boundary, the gas flow is not restricted or the amount of restriction is reduced. That is, the differential pressure generated between the vicinity of the elevating member and the other region in the bearing body is reduced, and the force for lifting the rotating shaft is reduced.

As a result, when the rotating shaft starts rotating from a stationary state or when the rotating shaft is rotating at a low speed, if the gas does not sufficiently circulate around the rotating shaft, the lifting member is lowered. By doing so, the force for lifting the rotating shaft can be increased, and the surface pressure that the bearing body receives from the rotating shaft can be reduced.
On the other hand, when the rotating shaft is rotating at a high speed and the gas is sufficiently encircling around the rotating shaft, the lifting member is lifted to reduce the force to lift the rotating shaft, and the rotating shaft It can be prevented that the bearing body is too lifted and comes into contact with the upper inner surface (lower surface of the elevating member) of the bearing body.

  A gas bearing according to the present invention is the gas bearing according to any one of claims 1 to 3, wherein the exhaust port is provided with a valve for controlling a gas flow rate. .

The gas bearing configured as described above operates between a region above the rotating shaft and a region below the rotation shaft in the bearing body by adjusting the amount of gas flowing through the exhaust port by operating the valve (discharge port). The pressure difference that occurs between the vicinity of and the other region can be adjusted.
For example, the internal pressure in the region above the rotating shaft can be reduced by opening the valve and ensuring the amount of gas flowing through the exhaust port. That is, it is possible to increase the differential pressure between the upper region and the lower region of the rotating shaft and increase the force for lifting the rotating shaft.
Moreover, the fall of the internal pressure of the area | region above a rotating shaft can be suppressed by closing the valve | bulb and reducing the distribution | circulation amount of the gas which distribute | circulates an exhaust port, or interrupt | blocking a distribution | circulation. That is, it is possible to reduce or eliminate the pressure difference between the upper region and the lower region of the rotating shaft, and to reduce or eliminate the force for lifting the rotating shaft.

Here, this valve may have a configuration that can take only one of the open state and the closed state.
Further, this valve may be configured such that the opening degree can be adjusted continuously or stepwise. In this case, by adjusting the opening degree of the valve, the amount of gas flowing in the exhaust port can be adjusted as appropriate, and the force for lifting the rotating shaft can be set to an optimum magnitude.

  A bearing device according to the present invention is a bearing device that supports a rotating shaft using the gas bearing according to claim 3, wherein the rotating speed detecting device detects the rotating speed of the rotating shaft, and the rotating speed detection device. And a control device that controls the operation of the lifting device based on the rotational speed of the rotating shaft detected by the device.

In the bearing device configured as described above, the rotational speed of the rotary shaft supported by the gas bearing is detected by the rotational speed detection device.
Based on the detected rotational speed of the rotating shaft, the control device controls the lifting operation of the lifting device.
Specifically, when the rotational speed of the rotating shaft is lower than a predetermined reference rotational speed, the control device operates the lifting device to lower the lifting member. Then, since the space formed between the elevating member and the rotating shaft is reduced, the differential pressure generated between the vicinity of the elevating member and the other region is increased in the bearing body. Thereby, the force which lifts a rotating shaft becomes large, and the surface pressure added to a bearing main body is reduced.
On the other hand, when the rotational speed of the rotating shaft is equal to or higher than the reference rotational speed, the control device operates the lifting device to raise the lifting member. Then, since the space formed between the raising / lowering member and the rotating shaft is increased, the differential pressure generated between the vicinity of the raising / lowering member and the other region is reduced in the bearing body. Thereby, the force which lifts a rotating shaft becomes small, and it can prevent that a rotating shaft is lifted too much and contacts the upper inner surface (lowering member lower surface) of a bearing main body.

  A bearing device according to the present invention is a bearing device that supports a rotary shaft using the gas bearing according to claim 4, and includes a rotational speed detection device that detects a rotational speed of the rotary shaft, and the rotational speed detection And a control device for controlling the opening / closing operation of the valve based on the rotational speed of the rotating shaft detected by the device.

In the bearing device configured as described above, the rotational speed of the rotary shaft supported by the gas bearing is detected by the rotational speed detection device.
Based on the detected rotational speed of the rotating shaft, the control device controls the valve opening / closing operation.
Specifically, when the rotation speed of the rotation shaft is lower than a predetermined reference rotation speed (that is, when the gas does not sufficiently circulate around the rotation shaft), the control device opens the valve. Thus, air is discharged from above the rotating shaft through an exhaust port provided in the upper part of the bearing body.
Then, the differential pressure generated between the upper portion of the rotating shaft and the other region is increased in the bearing body. Thereby, the force which lifts a rotating shaft can be enlarged, and the surface pressure which a bearing main body receives from a rotating shaft can be reduced.
On the other hand, when the rotational speed of the rotary shaft is equal to or higher than the reference rotational speed (that is, when the gas is sufficiently around the rotary shaft), the control device closes the valve and gas from the exhaust port. The pressure difference generated between the upper portion of the rotating shaft and the other region in the bearing body is reduced by stopping the discharge of the shaft or reducing the discharge amount. Thereby, the force which lifts a rotating shaft becomes small, and it prevents that a rotating shaft is lifted too much and contacts the upper inner surface of a bearing main body.

  The compressor according to the present invention is a compressor that compresses and sends out the gas taken into the casing by the impeller by rotationally driving the impeller provided in the casing by a driving device, The rotating shaft which connects an impeller and the output shaft of the said drive device is supported by the said casing via the gas bearing in any one of Claim 1 to 4, It is characterized by the above-mentioned.

  In the compressor configured as described above, the rotating shaft is supported by the gas bearing according to any one of claims 1 to 4. That is, since a gas bearing having a small surface pressure that the bearing body receives from the rotating shaft is used, a gas bearing that is smaller than a conventional gas bearing can be employed.

  The compressor according to the present invention is a compressor that compresses and sends out the gas taken into the casing by the impeller by rotationally driving the impeller provided in the casing by a driving device, A rotational speed detection device for detecting a rotational speed of the rotary shaft, wherein a rotary shaft connecting the impeller and the output shaft of the drive device is supported by the casing via the gas bearing according to claim 3. And a control device that controls the lifting operation of the lifting device based on the rotational speed of the rotating shaft detected by the rotational speed detection device.

In the compressor configured as described above, the rotational speed of the rotary shaft supported by the gas bearing is detected by the rotational speed detection device.
Based on the detected rotational speed of the rotating shaft, the control device controls the lifting operation of the lifting device.
Specifically, when the rotational speed of the rotating shaft is lower than a predetermined reference rotational speed, the control device operates the lifting device to lower the lifting member. Then, since the space formed between the elevating member and the rotating shaft is reduced, the differential pressure generated between the vicinity of the elevating member and the other region is increased in the bearing body. Thereby, the force which lifts a rotating shaft becomes large, and the surface pressure added to a bearing main body is reduced.
On the other hand, when the rotational speed of the rotating shaft is equal to or higher than the reference rotational speed, the control device operates the lifting device to raise the lifting member. Then, since the space formed between the raising / lowering member and the rotating shaft is increased, the differential pressure generated between the vicinity of the raising / lowering member and the other region is reduced in the bearing body. Thereby, the force which lifts a rotating shaft becomes small, and it can prevent that a rotating shaft is lifted too much and contacts the upper inner surface (lowering member lower surface) of a bearing main body.

  The compressor according to the present invention is a compressor that compresses and sends out the gas taken into the casing by the impeller by rotationally driving the impeller provided in the casing by a driving device, A rotational speed detection device for detecting a rotational speed of the rotary shaft, wherein a rotary shaft connecting the impeller and the output shaft of the drive device is supported by the casing via the gas bearing according to claim 4. And a control device for controlling the opening / closing operation of the valve based on the rotational speed of the rotating shaft detected by the rotational speed detecting device.

In the compressor configured as described above, the rotational speed of the rotary shaft supported by the gas bearing is detected by the rotational speed detection device.
Based on the detected rotational speed of the rotating shaft, the control device controls the valve opening / closing operation.
Specifically, when the rotation speed of the rotation shaft is lower than a predetermined reference rotation speed (that is, when the gas does not sufficiently circulate around the rotation shaft), the control device opens the valve. Thus, air is discharged from above the rotating shaft through an exhaust port provided in the upper part of the bearing body.
Then, the differential pressure generated between the upper portion of the rotating shaft and the other region is increased in the bearing body. Thereby, the force which lifts a rotating shaft can be enlarged, and the surface pressure which a bearing main body receives from a rotating shaft can be reduced.
On the other hand, when the rotational speed of the rotary shaft is equal to or higher than the reference rotational speed (that is, when the gas is sufficiently around the rotary shaft), the control device closes the valve and gas from the exhaust port. The pressure difference generated between the upper portion of the rotating shaft and the other region in the bearing body is reduced by stopping the discharge of the shaft or reducing the discharge amount. Thereby, the force which lifts a rotating shaft becomes small, and it prevents that a rotating shaft is lifted too much and contacts the upper inner surface of a bearing main body.

  The operation control method for a gas bearing according to the present invention includes a frictional resistance generated between the bearing body and the rotating shaft by forming a gas layer between the bearing body and the rotating shaft inserted through the bearing body. A gas bearing operation control method for supporting a rotating shaft in a reduced state using a gas bearing in which the bearing body is provided with a discharge port for discharging the gas in the bearing body from the top to the outside. When the rotation speed of the rotation shaft is lower than a predetermined reference rotation speed, the gas in the bearing body is discharged from the exhaust port, and the rotation speed of the rotation shaft is equal to or higher than the reference rotation speed. In this case, the discharge of the gas in the bearing body from the exhaust port is stopped or the discharge amount is reduced.

In this gas bearing operation control method, when the rotational speed of the rotating shaft is lower than a predetermined reference rotating speed, air is exhausted from above the rotating shaft through an exhaust port provided in the upper part of the bearing body. In the bearing body, the differential pressure generated between the upper part of the rotating shaft and the other region is increased. Thereby, the force which lifts a rotating shaft can be enlarged, and the surface pressure which a bearing main body receives from a rotating shaft can be reduced.
On the other hand, when the rotation speed of the rotation shaft is equal to or higher than the reference rotation speed, the gas discharge is stopped or the discharge amount is reduced, so that the upper portion of the rotation shaft and the other region in the bearing body. Reduce the differential pressure between the two. Thereby, the force which lifts a rotating shaft becomes small, and it prevents that a rotating shaft is lifted too much and contacts the upper inner surface of a bearing main body.

  The operation control method for a gas bearing according to the present invention includes a frictional resistance generated between the bearing body and the rotating shaft by forming a gas layer between the bearing body and the rotating shaft inserted through the bearing body. A gas bearing operation control method for supporting a rotating shaft in a reduced state, wherein the upper part of the inner surface of the bearing body as the gas bearing discharges the gas in the bearing body from the upper part to the outside. And a rotational speed of the rotary shaft is higher than a predetermined reference rotational speed using a gas bearing provided with a lifting device for moving the lifting member up and down. When it is low, the lifting device is operated to lower the lifting member so as to be close to the rotation shaft. When the rotation speed of the rotation shaft is equal to or higher than the reference rotation speed, the lifting device is operated. Lift the lifting member Was characterized be spaced from the axis of rotation.

In this gas bearing operation control method, when the rotational speed of the rotating shaft is lower than a predetermined reference rotational speed, the lifting device is operated to lower the lifting member. Then, since the space formed between the elevating member and the rotating shaft is reduced, the differential pressure generated between the vicinity of the elevating member and the other region is increased in the bearing body. Thereby, the force which lifts a rotating shaft becomes large, and the surface pressure added to a bearing main body is reduced.
On the other hand, when the rotational speed of the rotating shaft is equal to or higher than the reference rotational speed, the control device operates the lifting device to raise the lifting member. Then, since the space formed between the raising / lowering member and the rotating shaft is increased, the differential pressure generated between the vicinity of the raising / lowering member and the other region is reduced in the bearing body. Thereby, the force which lifts a rotating shaft becomes small, and it can prevent that a rotating shaft is lifted too much and contacts the upper inner surface (lowering member lower surface) of a bearing main body.

Here, in the operation control method of the bearing device, the compressor, and the gas bearing according to the present invention described above, the reference rotational speed means that a gas layer sufficient to support the rotating shaft is formed around the rotating shaft. This is the lower limit value of the rotational speed range that may be obtained, and this value is obtained by experiment, simulation, or the like.
In addition, as an index of the rotation speed of the rotation shaft, for example, an angular speed or a rotation speed is used.

According to the gas bearing of the present invention, a pressure difference is generated in the bearing body, and a force for lifting the rotating shaft is generated, so that the surface pressure that the bearing body receives from the rotating shaft is reduced.
As a result, in this gas bearing, even when the rotating shaft starts rotating from a stationary state or when the rotating shaft rotates at a low speed, the bearing body is not easily damaged, and the rotating shaft is well supported. It can be carried out. As a result, the bearing diameter can be minimized.

  Further, according to the bearing device of the present invention, the force for lifting the rotating shaft can be controlled according to the rotational speed of the rotating shaft, so that the rotating shaft can be favorably supported.

Moreover, according to the compressor concerning this invention, since a gas bearing smaller than the conventional gas bearing can be employ | adopted as a gas bearing, a compressor can be reduced in size.
Moreover, according to the compressor concerning this invention, since the force which lifts a rotating shaft can be controlled according to the rotational speed of a rotating shaft, a rotating shaft can be supported favorably.

  Further, according to the operation control method of the gas bearing according to the present invention, the force for lifting the rotating shaft can be controlled according to the rotational speed of the rotating shaft, so that the rotating shaft can be favorably supported.

Embodiments according to the present invention will be described below with reference to the drawings.
[First embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
As shown in FIG. 1, the compressor 1 shown in this embodiment includes a casing 2, a rotary shaft 3 provided in the casing 2 and driven to rotate by a driving device (not shown), and coaxial with the rotary shaft 3. And a centrifugal compressor having an impeller 4 provided to restrict relative rotation.
The compressor 1 rotates the impeller 3 by a driving device to rotate the impeller 4, thereby taking in the gas to be compressed from the suction portion 6 provided in the casing 2 and compressing the gas. Thus, the discharge is performed from the discharge portion 7 provided in the casing 2.

The rotating shaft 3 is supported through a gas bearing 11 according to the present invention in a state that allows rotation around the axis.
The gas bearing 11 that supports the radial direction of the rotary shaft 3 as described above has a bearing body 12 through which the rotary shaft 3 is inserted, as shown in FIG.
A discharge port 13 for discharging the working gas in the bearing body 12 to the outside is provided in the upper part of the bearing body 12. If the discharge port 13 is opened in the upper half region of the inner surface of the bearing body 12, the opening position thereof is arbitrary. In the present embodiment, the discharge port 13 is opened at the apex portion of the inner surface of the bearing body 12.
A working gas is supplied between the bearing body 12 and the rotary shaft 3 from a working gas supply source (not shown).

In the compressor 1 configured as described above, the rotation shaft 3 is allowed to rotate around the axis by fluid lubrication by the gas bearing 11.
Hereinafter, details of the support of the rotating shaft 3 by the gas bearing 11 will be described.

A working gas is supplied into the bearing body 12 at a high pressure from a working gas supply source. On the other hand, a discharge port 13 is provided at a position above the rotary shaft 3 in the bearing main body 12, and the working gas supplied into the bearing main body 12 is discharged out of the bearing main body 12 through the discharge port 13.
As a result, a pressure difference is generated between the area Su above the rotating shaft 3 and the area Sd below the rotating shaft 3 in the bearing body 12 (between the vicinity of the discharge port 13 and the other areas). The rotating shaft 3 is sucked up (or pushed up).

  In other words, as shown in FIG. 3, among the forces generated by receiving the pressure of the working gas supplied into the bearing body 12, the force Fd that pushes the rotating shaft 3 downward is applied to the rotating shaft 3. It becomes relatively small with respect to the force Fu that pushes the rotating shaft 3 upward. Thereby, the rotating shaft 3 is pushed upward by the force F obtained by subtracting the force Fd from the force Fu.

In the gas bearing 11, the force F that lifts the rotating shaft 3 is generated as described above, and therefore the surface pressure that the bearing body 12 receives from the rotating shaft 3 is reduced.
Thereby, in this gas bearing 11, even when the rotating shaft 3 starts rotating from a stationary state or when the rotating shaft 3 rotates at a low speed, the bearing main body 12 is hardly damaged, and the rotating shaft 3 Can be favorably supported. For this reason, although this gas bearing 11 is a gas bearing, the bearing diameter can be minimized.

  And in the compressor 1 concerning this embodiment, since the rotating shaft 3 is supported by the small gas bearing 11 in this way, the compressor 1 can be reduced in size.

Below, the effect obtained by this gas bearing 11 is demonstrated concretely using FIG.
The push-up force Fu [N] applied to the rotating shaft 3 when working gas is supplied to the gas bearing 11 is expressed by the following equation (1).
Fu = Ps × DL (1)
In the equation (1), Ps is the working gas supply pressure [Pa] to the gas bearing 11, D is the inner diameter [m] of the bearing body 12, and L is the effective bearing length [m] of the bearing body 12. .

On the other hand, the push-down force Fd [N] applied to the rotating shaft 3 is expressed by the following equation (2) assuming that the Su portion pressure is reduced by the effect of the exhaust port 13 and is reduced to α times Fu.
Fd = αFu = α × Ps × DL (2)
That is, the net pushing force F [N] generated by the differential pressure between the Su part and the Sd part is expressed by the following equation (3).
F = Fu−Fd = (1−α) × Ps × DL (3)

Therefore, the bearing surface pressure ΔP that can be reduced by adopting the configuration of the gas bearing 11 according to the present embodiment is expressed by the following equation (4).
ΔP = F / DL = (1-α) × Ps (4)

Here, in Equation (4), assuming that Ps is 100 kPa (gauge pressure) and α = 0.7, ΔP = 30 kPa.
Therefore, assuming that the design surface pressure of a gas bearing having a conventional configuration (hereinafter referred to as “conventional example”) is 30 kPa, a gas bearing (hereinafter referred to as “example”) in which the configuration shown in the present embodiment is applied to this gas bearing. ), The design surface pressure can be substantially increased up to 60 kPa by the above-described surface pressure reducing action.

This also means that the embodiment can be made smaller than the conventional example when the substantial design surface pressure is the same as that of the conventional example.
In the gas bearing, the surface pressure P [Pa] received by the bearing body is expressed by the following equation (5).
P = W / DL (5)
The inner diameter of the conventional bearing body is D ₁ [m], the effective bearing length of the bearing body is L ₁ [m], the inner diameter of the bearing body of the embodiment is D ₂ [m], and the effective bearing length of the bearing body is L Assuming ₂ [m], when the design surface pressure is 30 kPa, the surface pressure P ₁ [Pa] received by the bearing body of the conventional example and the surface pressure P ₂ [Pa] received by the bearing body of the example are: It is represented by the following formula (6).
P ₁ = W / D ₁ L ₁ = 30 [kPa], P ₂ = W / D ₂ L ₂ = 60 [kPa] (6)
W = 30D ₁ L ₁ = 60D ₂ L ₂
Therefore, D ₂ L ₂ = 0.5D ₁ L ₁
Here, in the gas bearing, the ratio between the inner diameter D [m] of the bearing body and the effective shaft length L [m] is set to a constant value β. That is, in the gas bearing, the relationship DL = βD ² is established.
When this relationship is applied to the equation (6), the following equation (7) is obtained.
βD ₂ ² = 0.5βD ₁ ² (7)
By arranging this, the following equation (8) is obtained.
D ₂ ² = 0.5D ₁ ² (8)
Solving equation (8) yields D ₂ = 0.7D ₁ .
That is, in the embodiment, when the substantial design surface pressure is the same as that of the conventional example, the bearing diameter can be reduced to 70% as compared with the conventional example.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
The compressor shown in the present embodiment uses a gas bearing 21 as a bearing that supports the rotary shaft 3. Hereinafter, the same or the same configuration as that of the compressor 1 shown in the first embodiment is denoted by the same reference numeral, and detailed description thereof is omitted.
This gas bearing 21 is obtained by changing the configuration of the bearing body 12 of the gas bearing 11 shown in the first embodiment.
Specifically, the bearing main body 21 used in the gas bearing 21 is a bearing main body 22 in which the vicinity of the discharge port 13 on the inner surface of the bearing main body 12 is a protruding portion 22a that protrudes radially inward as compared with other regions. It is what has.

The gas bearing 21 configured in this manner has a protruding portion 22a in the vicinity of the discharge port 13 in the inner surface of the bearing body 22, and the distance between the rotary shaft 3 is narrower than in other regions. Therefore, in the bearing body 22, the flow of the working gas is restricted at the boundary between the other region and the protruding portion 22a.
For this reason, a differential pressure is reliably generated between the region in the vicinity of the protrusion 22a and the other region in the bearing body 22 (that is, between the region Su above and the region Sd below the rotation shaft 3). Can be made.
Further, with this configuration, the differential pressure generated between the upper region Su and the lower region Sd of the rotating shaft 3 is increased, and the force for lifting the rotating shaft 3 is increased.
Thereby, the surface pressure applied to the bearing body 22 can be reliably and effectively reduced, and the rotation shaft 3 can be favorably supported while minimizing the bearing diameter.

  And in the compressor concerning this embodiment, since the rotating shaft 3 is supported by the small and high performance gas bearing 21 in this way, a compressor can be reduced in size.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.
The compressor shown in the present embodiment is mainly characterized in that the rotary shaft 3 is supported by using the bearing device 31 in the compressor 1 shown in the first embodiment.
Hereinafter, the same or the same configuration as that of the compressor 1 shown in the first embodiment is denoted by the same reference numeral, and detailed description thereof is omitted.

The bearing device 31 supports the rotating shaft 3 using the gas bearing 11 shown in the first embodiment. Further, the exhaust port 13 of the gas bearing 11 is provided with a valve 32 that controls the flow amount of the working gas through the exhaust port 13 directly or via a pipe.
Further, the bearing device 31 controls the opening / closing operation of the valve 32 based on the rotation speed detection device 33 that detects the rotation speed of the rotation shaft 3 and the rotation speed of the rotation shaft 3 detected by the rotation speed detection device 33. And a control device 34.

  In the bearing device 31 configured as described above, the flow of the working gas through the exhaust port 13 is controlled by controlling the opening and closing of the valve 32, so that the region above and below the rotating shaft 3 in the bearing body 12. It is possible to adjust the pressure difference that occurs between the first and second regions (between the vicinity of the discharge port 13 and other regions).

Specifically, the internal pressure in the region above the rotating shaft 3 can be reduced by opening the valve 32 and securing the flow amount of the working gas flowing through the exhaust port 13. That is, it is possible to increase the differential pressure between the upper region and the lower region of the rotating shaft 3 and increase the force for lifting the rotating shaft 3.
Further, by reducing the flow amount of the working gas flowing through the exhaust port 13 by closing the valve 32 or blocking the flow, it is possible to suppress a decrease in internal pressure in the region above the rotating shaft 3. That is, the differential pressure between the upper region and the lower region of the rotating shaft 3 can be reduced or eliminated, and the force for lifting the rotating shaft 3 can be reduced or eliminated.

  In the bearing device 31, the opening / closing of the valve 32 is controlled by the control device 34. The control device 34 controls the opening / closing of the valve 32 based on information on the rotational speed of the rotary shaft 3 detected by the rotational speed detection device 33. Here, as an index of the rotation speed of the rotating shaft 3, for example, an angular speed or a rotation speed is used.

Specifically, when the rotation speed of the rotation shaft 3 is lower than a predetermined reference rotation speed (that is, when the working gas does not sufficiently circulate around the rotation shaft 3), the control device 34 The valve 32 is opened to generate a force that lifts the rotating shaft, and the surface pressure that the bearing body 12 receives from the rotating shaft 3 is reduced.
On the other hand, when the rotational speed of the rotary shaft 3 is equal to or higher than the reference rotational speed (that is, when the working gas sufficiently circulates around the rotary shaft 3), the control device 34 closes the valve 32 and exhausts the exhaust gas. The discharge of the working gas from the port 13 is stopped or the discharge amount is reduced, the force for lifting the rotating shaft 3 is reduced, and the rotating shaft 3 is lifted too much to contact the upper inner surface of the bearing body 12. Can be prevented.
In other words, in the compressor according to the present embodiment, the support state of the rotary shaft 3 can be adjusted according to the number of rotations of the rotary shaft 3 to always provide optimum support.

  Here, the reference rotation speed is a lower limit value of a rotation speed range in which a working gas layer sufficient for supporting the rotation shaft 3 is formed around the rotation shaft 3. It is required by experiment and simulation.

Further, the valve 32 may be configured to be able to take only one of the open state and the closed state, or may be configured to be able to adjust the opening degree continuously or stepwise.
When the valve 32 has a configuration in which the opening degree can be adjusted continuously or stepwise, by adjusting the opening degree of the valve 32, the flow amount of the working gas at the exhaust port 13 is appropriately adjusted, The force for lifting the rotating shaft 3 can be set to an optimum magnitude.

  Here, in the present embodiment, an example in which the bearing device 31 is configured to support the rotating shaft 3 by the gas bearing 11 shown in the first embodiment is shown. It is good also as a structure which supports the rotating shaft 3 with the gas bearing 21 shown by embodiment.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG.
The compressor shown in this embodiment is mainly characterized in that the rotary shaft 3 is supported by using the bearing device 41 in the compressor 1 shown in the first embodiment.
Hereinafter, the same or the same configuration as that of the compressor 1 shown in the first embodiment is denoted by the same reference numeral, and detailed description thereof is omitted.

The bearing device 41 uses the gas bearing 42 to support the rotating shaft 3.
In the gas bearing 11 shown in the first embodiment, the gas bearing 42 is a bearing in which the upper part of the inner surface has a discharge port 13 and is movable up and down instead of the bearing body 12. The main body 44 is used. The bearing body 44 is provided with a lifting device 45 that lifts and lowers the lifting member 43.

The bearing body 44 is provided with a recess 44a that opens to the upper inner surface. A chamber 44b is provided above the recess 44a.
The elevating member 43 is inserted into the bearing body 44 from the inside of the recess 44a to the upper surface of the bearing body 44 through the chamber 44b, and is provided to be slidable in the vertical direction with respect to the bearing body 44. .
The elevating member 43 has a lower portion 43 a whose lower surface forms the upper inner surface of the bearing body 44, and an overhang portion 43 b that projects sideways above the lower portion 43 a. Further, the elevating member 43 is provided with an exhaust port 13 leading from the lower end surface to the upper end.
The elevating member 43 is inserted into the bearing body 44 with the lower portion 43a positioned in the recess 44a and the overhanging portion 43b positioned in the chamber 44b. Here, the overhanging portion 43b also serves as a partition that partitions the inside of the chamber 44b into the upper space S1 and the lower space S2.
Here, in the lower space S2, the working gas in the bearing body 44 is supplied little by little through the gap between the bearing body 44 and the elevating member 43, and the internal pressure is equal to or higher than atmospheric pressure. Is secured.

The elevating device 45 is provided in the lower space S2 and is a coil spring 46 that urges the protruding portion 43b of the elevating member 43 upward, and a tube that connects the lower space S2 and the outside of the bearing body 44. A passage 47 and a valve 48 for controlling the flow rate of the working gas through the conduit 47 are provided.
Further, the lifting device 45 controls the opening / closing operation of the valve 48 based on the rotation speed detection device 49 that detects the rotation speed of the rotation shaft 3 and the rotation speed of the rotation shaft 3 detected by the rotation speed detection device 49. And a control device 50.

  In the bearing device 41 configured as described above, the support state of the rotary shaft 3 is adjusted by moving the lifting member 43 provided on the bearing body 44 of the gas bearing 42 up and down.

Below, the raising / lowering operation | movement of the raising / lowering member 43 is demonstrated.
In the chamber 44b of the bearing body 44, the working gas is supplied little by little from the inside of the bearing body 44 to the space S2 located below the protruding portion 43b of the elevating member 43 as described above.
The space S2 communicates with the outside of the bearing main body 44 through a pipe 47, and the working gas in the space S2 is released out of the bearing main body 44 by opening the valve 48.
That is, by opening the valve 48, the internal pressure of the space S2 is reduced, and a pressure difference is generated between the space S1 and the space S2.
This pressure difference (the pressure in the space S1−the pressure in the space S2) acts to press the protruding portion 43b of the elevating member 43 downward. Then, the pressing force applied to the overhanging portion 43b by this pressure difference overcomes the biasing force of the coil spring 46 that biases the overhanging portion 43b upward, so that the overhanging portion 43b moves downward. Thus, the elevating member 43 is lowered.

  When the elevating member 43 moves downward as described above, the amount of elastic deformation of the coil spring 46 increases, so that the urging force of the coil spring 46 increases. The elevating member 43 stops at a position where the force generated by the difference in internal pressure between the spaces S <b> 1 and S <b> 2 antagonizes the urging force of the coil spring 46.

On the other hand, by closing the valve 48, the working gas supplied into the bearing main body 44 gradually flows into the space S2, and the internal pressure rises again. That is, by closing the valve 48, the internal pressure of the space S2 rises again, and the pressure difference between the space S1 and the space S2 decreases. Then, by the urging force of the coil spring 46, the overhanging portion 43b moves upward, and the elevating member 43 is raised.
That is, when the force generated by the difference in internal pressure between the spaces S1 and S2 becomes smaller than the biasing force of the coil spring 46, the elevating member 43 moves upward.

  When the elevating member 43 moves upward as described above, the coil spring 46 approaches the original length, so that the urging force of the coil spring 46 is reduced. The elevating member 43 stops at a position where the force generated by the difference in internal pressure between the spaces S <b> 1 and S <b> 2 antagonizes the urging force of the coil spring 46.

Thus, in this bearing device 41, the elevating member 43 is raised and lowered by controlling the opening and closing of the valve 48.
When the elevating member 43 is lowered in this manner and the distance between the lower portion 43a of the elevating member 43 and the rotary shaft 3 is reduced, the space formed between the elevating member 43 and the rotary shaft 3 is reduced. In the bearing main body 44, the flow of the working gas is restricted at the boundary between the vicinity of the lower portion 43a and the other region. That is, in the bearing main body 44, the differential pressure generated between the vicinity of the lower portion 43a and the other region is increased, and the force for lifting the rotary shaft 3 is increased.

  On the other hand, the space formed between the lower part 43a of the elevating / lowering member 43 and the rotary shaft 3 is increased by raising and lowering the elevating / lowering member 43 from the rotary shaft 3, so that the lower part 43a in the bearing body 44 is increased. The flow of the working gas is not restricted or the amount of restriction is reduced at the boundary between the vicinity of the region and the other region. That is, in the bearing main body 44, the differential pressure generated between the vicinity of the lower portion 43a and the other region is reduced, and the force for lifting the rotary shaft 3 is reduced.

  Here, in the bearing device 41, the opening and closing of the valve 48 is controlled by the control device 50. The control device 50 controls the opening and closing of the valve 48 based on information on the rotational speed of the rotary shaft 3 detected by the rotational speed detection device 49. Here, as an index of the rotation speed of the rotating shaft 3, for example, an angular speed or a rotation speed is used.

Specifically, when the rotation speed of the rotation shaft 3 is lower than a predetermined reference rotation speed (that is, when the working gas does not sufficiently circulate around the rotation shaft 3), the control device 50 The valve 48 is opened, the elevating member 43 is lowered to generate a force for lifting the rotating shaft 3, and the surface pressure that the bearing body 44 receives from the rotating shaft 3 is reduced.
On the other hand, when the rotational speed of the rotary shaft 3 is equal to or higher than the reference rotational speed (that is, when the working gas has sufficiently circulated around the rotary shaft 3), the control device 50 closes the valve 48 and moves up and down. The force which raises the member 43 and raises the rotating shaft 3 is made small, and the rotating shaft 3 is prevented from being lifted too much and coming into contact with the upper inner surface of the bearing body 44.
In other words, in the compressor according to the present embodiment, the support state of the rotary shaft 3 can be adjusted according to the number of rotations of the rotary shaft 3 to always provide optimum support.

  Here, the reference rotation speed is a lower limit value of a rotation speed range in which a working gas layer sufficient for supporting the rotation shaft 3 is formed around the rotation shaft 3. It is required by experiments and simulations.

Further, the valve 48 may be configured to be able to take only one of the open state and the closed state, and may be configured to be able to adjust the opening degree continuously or stepwise.
When the valve 48 is configured so that the opening degree thereof can be adjusted continuously or stepwise, the vertical position of the elevating member 43 (that is, the lower part 43a of the elevating member 43 is adjusted by adjusting the opening degree of the valve 48. The size of the space formed between the rotating shaft 3 and the rotating shaft 3 can be adjusted as appropriate, so that the force for lifting the rotating shaft 3 can be set to an optimum size.

Here, in the bearing device 41 according to the present embodiment, as shown in the third embodiment, a valve 32, a rotational speed detection device 33, and a control device 34 are provided, and the working gas from the discharge port 13 is provided. It is good also as a structure which can control discharge | emission of this.
In this case, in addition to the adjustment of the support state of the rotating shaft 3 by raising and lowering the lifting member 43, the support state of the rotating shaft 3 can be further adjusted by controlling the discharge amount of the working gas from the discharge port 13. It is possible to control the support state of the rotary shaft 3 more appropriately.

It is a longitudinal cross-sectional view which shows the structure of the compressor and bearing apparatus concerning 1st embodiment of this invention. It is an axis orthogonal sectional view showing composition of a bearing device concerning a first embodiment of the present invention, and a gas bearing. It is an axial orthogonal cross section which shows the effect | action of the gas bearing concerning 1st embodiment of this invention. It is an axial orthogonal cross section which shows the structure of the bearing apparatus concerning 2nd embodiment of this invention, and a gas bearing. It is an axial orthogonal cross section which shows the structure of the bearing apparatus used with the compressor concerning 3rd embodiment of this invention. It is an axial orthogonal cross section which shows the structure of the bearing apparatus used with the compressor concerning 4th embodiment of this invention.

Explanation of symbols

1 Compressor 2 Casing 3 Rotating shaft 4 Impeller 11, 21, 42 Gas bearing 12, 22, 44 Bearing body 13 Discharge port 22 a Protruding part 31, 41 Bearing device 32 Valve 33, 49 Rotational speed detecting device 34, 50 Control device 43 Lifting member 45 Lifting device

Claims (11)

A gas bearing that supports a radial direction of the rotary shaft by forming a gas layer between the bearing main body and the rotary shaft inserted through the bearing main body,
A gas bearing according to claim 1, wherein the bearing body is provided with a discharge port for discharging the gas in the bearing body from the top to the outside.   2. The gas bearing according to claim 1, wherein the inner surface of the bearing body has a protruding portion that protrudes radially inward in the vicinity of the discharge port as compared with other regions. The upper part of the inner surface of the bearing body is constituted by a lifting member that has the discharge port and is movable in the vertical direction,
The gas bearing according to claim 1, wherein the bearing body is provided with a lifting device that lifts and lowers the lifting member.   The gas bearing according to any one of claims 1 to 3, wherein the exhaust port is provided with a valve for controlling a discharge amount of the gas from the exhaust port. A bearing device for supporting a rotating shaft using the gas bearing according to claim 3,
A rotational speed detection device for detecting the rotational speed of the rotary shaft;
A bearing device comprising: a control device that controls the operation of the lifting device based on the rotational speed of the rotary shaft detected by the rotational speed detection device. A bearing device for supporting a rotating shaft using the gas bearing according to claim 4,
A rotational speed detection device for detecting the rotational speed of the rotary shaft;
And a control device for controlling the opening / closing operation of the valve based on the rotational speed of the rotating shaft detected by the rotational speed detecting device. A compressor for rotating and driving an impeller provided in a casing by a driving device so that the gas taken into the casing is compressed by the impeller and sent out. The output shaft of the impeller and the driving device The compressor is characterized in that a rotating shaft that connects the two is supported by the casing via the gas bearing according to any one of claims 1 to 4. A compressor that compresses and sends out the gas taken into the casing by the impeller by rotationally driving the impeller provided in the casing by a driving device,
A rotating shaft that connects the impeller and the output shaft of the driving device is supported by the casing via the gas bearing according to claim 3,
A rotational speed detection device for detecting the rotational speed of the rotary shaft;
A compressor comprising: a control device that controls a lifting operation of the lifting device based on a rotational speed of the rotating shaft detected by the rotational speed detection device. A compressor that compresses and sends out the gas taken into the casing by the impeller by rotationally driving the impeller provided in the casing by a driving device,
A rotating shaft that connects the impeller and the output shaft of the driving device is supported by the casing via the gas bearing according to claim 4,
A rotational speed detection device for detecting the rotational speed of the rotary shaft;
And a control device that controls the opening / closing operation of the valve based on the rotation speed of the rotation shaft detected by the rotation speed detection device. A gas that supports the rotating shaft in a state where a frictional resistance generated between the bearing body and the rotating shaft is reduced by forming a gas layer between the bearing body and the rotating shaft inserted through the bearing body. A bearing operation control method comprising:
As the gas bearing, the upper part of the inner surface of the bearing body has a discharge port for discharging the gas in the bearing body from the upper part to the outside, and is configured by a lifting member that can move in the vertical direction. Using a gas bearing provided with a lifting device
When the rotational speed of the rotating shaft is lower than a predetermined reference rotating speed, the lifting device is operated to lower the lifting member to approach the rotating shaft,
When the rotational speed of the rotating shaft is equal to or higher than the reference rotational speed, the operation control method for a gas bearing is characterized in that the lifting device is moved up and separated from the rotating shaft by operating the lifting device. A gas that supports the rotating shaft in a state where a frictional resistance generated between the bearing body and the rotating shaft is reduced by forming a gas layer between the bearing body and the rotating shaft inserted through the bearing body. A bearing operation control method comprising:
In the bearing body, using a gas bearing provided with a discharge port for discharging the gas in the bearing body from the top to the outside,
When the rotational speed of the rotating shaft is lower than a predetermined reference rotational speed, the gas in the bearing body is discharged from the exhaust port,
When the rotational speed of the rotating shaft is equal to or higher than the reference rotational speed, the gas bearing is characterized in that the exhaust of the gas in the bearing body from the exhaust port is stopped or the exhaust amount is reduced. Operation control method.

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