JP2015175418A - Bearing device and rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict a contacted state or increasing in temperature of a bearing pad by restricting inclination of the bearing pad.SOLUTION: A bearing device 62 comprises a plurality of bearing pads 24 spaced apart in a circumferential direction while being oppositely faced against a thrust collar 31 extending from a rotating shaft 30 rotated around an axial line toward a radial outer side and supporting members 23 for oscillatably supporting each of the bearing pads 24 through contact point from an opposite side facing against the thrust collar 31. A point contact position P between the bearing pad 24 and the supporting member 23 is positioned more inside in a radial direction than a center C1 of a size in a radial direction of the bearing pad 24.

Description

  The present invention relates to a bearing device including a bearing pad and a rotary machine including the bearing device.

In a rotary machine having a rotating shaft such as a steam turbine, a gas turbine, a pump, and an engine, a bearing device is used to rotatably support the rotating shaft.
As such a bearing device, there are a journal bearing and a thrust bearing provided with a bearing pad having a pad surface slidably contacting a rotating shaft.

  Among these, the thrust bearing supports the load in the thrust direction of the rotating shaft by the bearing pad. The rotating shaft is provided with a disk-shaped thrust collar that projects outward in the radial direction. The bearing pad has a pad surface facing the thrust collar in the axial direction of the rotary shaft, and a plurality of bearing pads are provided at intervals in the circumferential direction. Each bearing pad is supported by a pivot so that the back surface opposite to the pad surface can swing.

  Lubricating oil is interposed between the pad surface of the bearing pad and the thrust collar. Thus, an oil film is formed between the pad surface and the thrust collar, and a thrust load is transmitted between the bearing pad and the thrust collar by the pressure (oil film pressure) generated by the oil film.

Therefore, in order for the bearing pad to efficiently transmit the thrust load, the pad surface is preferably parallel to the thrust collar, and the oil film pressure between the pad surface and the thrust collar is preferably uniform.
Thus, for example, Patent Documents 1 and 2 disclose a configuration in which the pivot position is offset in the circumferential direction of the rotation shaft with respect to the bearing pad in order to suppress the inclination with respect to the thrust collar.

JP-A-5-231423 Special table 2012-529611 gazette

However, when the lubricating oil is not sufficient, there may be a region where the pad surface is not partially wetted with oil between the bearing pad and the thrust collar arranged in the upper half of the bearing device.
FIG. 6 shows an example of an oil wet state on the pad surface 200 a of the bearing pad 200. For example, as shown in FIG. 6 (a), a region A1 that is not wetted with oil is generated on the pad surface 200a on the front end side in the rotational direction on the outer peripheral side with respect to the rotational direction R of the rotational shaft.
When the rotor is rotated in such a state, as shown in FIG. 6B, a distribution is generated in the oil film pressure between the pad surface 200a and the thrust collar, and regions A2, A3 where the oil film pressure is low on the outer peripheral side. Occurs.

Thus, if the oil film pressure distribution between the bearing pad and the thrust collar is biased, the bearing pad is inclined. As a result, a part of the bearing pad comes into contact with the thrust collar, or the clearance between the bearing pad and the thrust becomes excessively small, resulting in an increase in the lubricating oil temperature and an increase in the temperature of the pad surface.
Accordingly, an object of the present invention is to provide a bearing device and a rotating machine that can suppress contact of the bearing pad and temperature rise by suppressing inclination of the bearing pad.

The present invention employs the following means in order to solve the above problems.
That is, the bearing device according to the present invention is directed to a thrust collar that projects radially outward from a rotating shaft that rotates about an axis, and a plurality of bearing pads that are spaced apart in the circumferential direction, and each of the bearing pads. And a support member that swingably supports by point contact from a side opposite to the side facing the thrust collar, and a point contact position between the bearing pad and the support member is a radial dimension of the bearing pad. It is located in the radial direction inner side from the center of.

  In such a configuration, the point contact position between the bearing pad and the support member, that is, the area of the pad surface of the bearing pad on the outer peripheral side with respect to the pivot center of the bearing pad is greater on the pad surface on the inner peripheral side than the pivot center. It becomes larger than the area. Then, the moment of load due to the oil film pressure of the lubricating oil interposed between the bearing pad and the thrust collar on the outer peripheral side from the pivot center increases. Thereby, since the amount of lubricating oil is small, the inclination of the bearing pad can be suppressed even in the case where the bearing pad is inclined in the radial direction outer peripheral side.

The distance D from the inner peripheral edge of the bearing pad to the point contact position is preferably 0.44L ≦ D ≦ 0.48L with respect to the radial dimension L of the bearing pad.
Furthermore, the distance D from the inner peripheral edge of the bearing pad to the point contact position may be 0.42L ≦ D ≦ 0.48L with respect to the radial dimension L of the bearing pad.
If the point contact position is excessively positioned on the inner side in the radial direction, the bearing pad is inclined toward the inner peripheral side, and the clearance on the inner peripheral side is reduced. Therefore, the distance D is preferably 42% to 48% of the radial dimension L, or 42% to 48%. As a result, an increase in the bearing metal temperature can be suppressed.

  A rotating machine according to the present invention has a thrust collar that projects radially outward, and includes a rotating shaft that rotates around an axis and a bearing device as described above.

  With such a configuration, since the amount of lubricating oil is small, the inclination of the bearing pad can be suppressed even if the bearing pad is inclined in the radial direction outer periphery side in the prior art.

  According to the bearing device and the rotating machine of the present invention, since the inclination of the bearing pad can be suppressed, the contact of the bearing pad and the temperature rise can be suppressed.

It is a figure which shows the structure of the steam turbine as an example of the rotary machine which concerns on this embodiment. It is a figure which shows schematic structure of the thrust bearing which concerns on this embodiment, and is a half sectional view in the direction along the central axis of a rotating shaft. It is a figure which shows schematic structure of a thrust bearing, and is sectional drawing orthogonal to the central axis of a rotating shaft. It is a figure which shows the pivot position in a bearing pad. It is a figure which shows the pivot position in the bearing pad of a thrust bearing in the modification of this embodiment. (A) is a figure which shows distribution of the area | region which does not get wet with oil in a pad surface, (b) is a figure which shows distribution of the area | region where an oil film pressure is especially low in a pad surface. It is a simulation result which shows the relationship between D / L and bearing metal temperature.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out bearing pads, bearings, and rotating machines according to the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited only to this embodiment.
First, a steam turbine (rotary machine) 100 according to an embodiment of the present invention will be described.
As shown in FIG. 1, the steam turbine 100 is an external combustion engine that extracts the energy of the steam S as rotational power, and is used for a generator in a power plant.

The steam turbine 100 includes a turbine casing 90, a rotating shaft 30 extending along the axis O so as to penetrate the turbine casing 90, a stationary blade 40 held by the turbine casing 90, and a motion provided on the rotating shaft 30. A blade 70 and a bearing portion 60 that supports the rotary shaft 30 so as to be rotatable around the axis O are provided.
In addition, the bearing part 60 is provided with the journal bearing 61 and the thrust bearing (bearing apparatus) 62, and is supporting the rotating shaft 30 rotatably.

As shown in FIGS. 2 and 3, the thrust bearing 62 is provided so as to project radially outward from the rotating shaft 30 of the turbine, and rotates in the rotating direction R together with the rotating shaft 30, for example. 31 is rotatably supported so as to be sandwiched from both axial sides of the rotating shaft 30. Accordingly, the thrust bearing 62 supports a load (displacement) in the axial direction (thrust direction) of the rotary shaft 30.
The thrust bearing 62 includes a bearing casing 22, support members 23 provided at equal angular intervals in the bearing casing 22, and bearing pads 24 that are swingably supported by the respective support members 23.

  The bearing casing 22 extends from the cylindrical outer peripheral wall portion 22a provided on the outer peripheral side of the thrust collar 31 to the inner peripheral side from one end side and the other end side of the outer peripheral wall portion 22a. , 31b and annular support wall portions 22b, 22c facing each other with a gap. The support wall portions 22 b and 22 c are formed so that the inner diameter thereof is larger than the outer diameter of the rotary shaft 30 so as not to interfere with the rotary shaft 30.

  The support members 23 are provided at equal angular intervals in the circumferential direction of the rotary shaft 30 on the side facing the thrust collar 31 in each of the support wall portions 22 b and 22 c of the bearing casing 22. Each support member 23 is formed so as to protrude from the support wall portions 22 b and 22 c of the bearing casing 22 to the side facing the thrust collar 31. An end portion of the support member 23 in the protruding direction, that is, a contact portion with the back surface of the bearing pad 24 is formed in a spherical shape.

In the bearing casing 22, the same number of bearing pads 24 as the support members 23 are provided on both sides of the thrust collar 31 at intervals in the circumferential direction of the rotary shaft 30. Each bearing pad 24 is provided with a pad surface 24 p formed on one surface thereof facing the thrust collar 31.
Each bearing pad 24 is supported by a support member 23 on the back side opposite to the pad surface 24p and is swingably provided. The support member 23 and the bearing pad 24 are in a contact state by point contact, and are misaligned between the thrust collar 31 of the rotating shaft 30 and the thrust bearing 62 (the outer peripheral surface of the rotating shaft 30 and the pad surface 24p of the bearing pad 24). The bearing pad 24 can follow the rotating shaft 30.

  Each bearing pad 24 has a fan-like shape having a certain thickness. For example, a back metal member 24h formed of iron, chrome steel, or the like, a white metal formed on a fan-like surface on one side of the back metal member 24h, And a pad surface 24p formed of PTFE (polytetrafluoroethylene), PEEK (polyetheretherketone) resin, or the like.

  As shown in FIG. 4, in the thrust bearing 62, the point contact position between the bearing pad 24 and the support member 23, that is, the pivot center P of the bearing pad 24 is radially inward from the center C1 of the radial dimension of the bearing pad 24. The position of the support member 23 is set so as to be positioned.

Thereby, the area of the pad surface 24p of the bearing pad 24 on the outer peripheral side with respect to the pivot center P becomes larger than the area of the pad surface 24p on the inner peripheral side with respect to the pivot center P. Then, as compared with the case where the pivot center P is positioned at the center C1 of the radial dimension of the bearing pad 24, the lubricating oil interposed between the bearing pad 24 and the thrust collar 31 on the outer peripheral side of the pivot center P is reduced. The moment of load due to oil film pressure increases.
Therefore, since the amount of lubricating oil is small, even if the bearing pad 24 is inclined in the radial direction outer peripheral side in the prior art, the load moment due to the oil film pressure on the outer peripheral side from the pivot center P is increased. By increasing, it becomes possible to balance the moment of load between the outer peripheral side and the inner peripheral side of the pivot center P. As a result, the inclination of the bearing pad 24 is suppressed.

The distance D from the inner peripheral edge of the bearing pad 24 to the pivot center P, which is the point contact position, is relative to the radial dimension L of the bearing pad 24.
0.44L ≦ D ≦ 0.48L
Is preferable,
0.42L ≦ D ≦ 0.48L
It is good.
If the pivot center P is excessively positioned radially inward, the bearing pad 24 is inclined toward the inner peripheral side, and the inner peripheral clearance becomes small. Therefore, the distance D is preferably 44% or more or 42% or more of the radial dimension L.

According to the thrust bearing 62 and the steam turbine 100 as described above, the pivot center P that is the point contact position of the bearing pad 24 is positioned radially inward from the center C1 of the radial dimension of the bearing pad 24. The inclination of the bearing pad 24 can be suppressed. As a result, the oil film thickness of the lubricating oil in the clearance portion between the pad surface 24p of the bearing pad 24 and the thrust collar 31 can be made uniform.
Further, by suppressing the inclination of the bearing pad 24 toward the outer peripheral side, the portion where the clearance between the pad surface 24p of the bearing pad 24 and the thrust collar 31 is the smallest, that is, the position where the oil film pressure is the smallest and the oil film pressure is the highest. However, it will be closer to the inner circumference. Therefore, the pivot center P is close to the position where the oil film pressure becomes maximum, and it is easy to balance the load moment due to the oil film pressure.
As a result, it is possible to suppress contact of the bearing pad 24 and an increase in the lubricating oil temperature and the metal temperature.

In addition, the structure shown by the said embodiment is applicable not only when the amount of lubricating oil is small but when the amount of lubricating oil is sufficient.
In this case, the position where the oil film pressure is maximized by suppressing the inclination of the bearing pad 24 toward the outer peripheral side is closer to the inner peripheral side. Further, in the clearance portion between the pad surface 24p of the bearing pad 24 and the thrust collar 31, the lubricating oil on the radially inner side where the relative peripheral speed between the bearing pad 24 and the thrust collar 31 is small can easily flow. The temperature of the lubricating oil interposed between the bearing pad 24 and the thrust collar 31, that is, the metal temperature can be lowered.

(Other embodiments)
The bearing device and the rotating machine of the present invention are not limited to the above-described embodiment described with reference to the drawings, and various modifications can be considered within the technical scope.
For example, as shown in FIG. 5, the bearing pad 24 of the thrust bearing 62 has a point contact position with the support member 23, that is, the pivot center P of the bearing pad 24 is more radial than the center C1 of the radial dimension of the bearing pad 24. The position of the support member 23 is set so as to be located on the inner side and offset to the rear edge side of the bearing pad 24 in the circumferential direction of the bearing pad 24.
Here, the pivot center P is such that the dimension T from the circumferential front edge 24f of the bearing pad 24 is 0.65W ≦ T, where W is the circumferential length of the bearing pad 24. Is preferred.

  In such a configuration, even when the amount of the lubricating oil is insufficient, the load due to the oil film pressure of the lubricating oil is large because the area of the pad surface 24p on the upstream side with respect to the rotation direction R with respect to the pivot center P is large. The moment of does not drop excessively. Therefore, in the circumferential direction of the bearing pad 24, it is easy to balance the moment of load due to the oil film pressure on the upstream side and the downstream side in the rotational direction of the pivot center P. As a result, the inclination of the bearing pad 24 can be suppressed also in the circumferential direction.

Further, the rotary machine including the bearing as described above is not limited to a steam turbine, and may be a gas turbine, a pump, an engine, a wind power generator, a windmill, a water wheel, or the like.
In addition to this, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate without departing from the gist of the present invention.

Examples will be described below.
For a thrust bearing having the same configuration as that of the embodiment, the temperature of the bearing pad (bearing metal) when the size of the distance D from the inner peripheral edge of the bearing pad to the point contact position is changed with respect to the radial dimension L of the bearing pad. The temperature was simulated.
More specifically, the temperature of the bearing metal is simulated when D = 0.38L, 0.40L, 0.42L, 0.44L, 0.46L, 0.48L, 0.50L, 0.52L. It was. The simulation result is shown in FIG.
The rotational speed of the rotating shaft was 3000 rpm, and the oil supply temperature was 40 ° C.

From the results shown in FIG. 7, it was found that when 0.42L ≦ D ≦ 0.48L, the bearing metal temperature is less than 90 °, and the temperature rise can be suppressed.
Further, it was found that the bearing metal temperature can be further suppressed when 0.44L ≦ D ≦ 0.48L.
In addition, it turned out that the temperature suppression effect of a bearing metal temperature is most highly acquired by setting it as D = 0.46L.
From the above, it was found that the bearing metal temperature can be satisfactorily suppressed by satisfying 0.42L ≦ D ≦ 0.48L or 0.44L ≦ D ≦ 0.48L.

22 Bearing casing 23 Support member 24 Bearing pad 24p Pad surface 24q Back surface 30 Rotating shaft 31 Thrust collar 34 Each bearing pad 40 Stator blade 60 Bearing portion 61 Journal bearing 62 Thrust bearing (bearing device)
70 Moving blade 90 Turbine casing 100 Steam turbine (rotary machine)
D Distance P Pivot center (point contact position)

Claims (4)

A bearing pad facing a thrust collar that projects radially outward from a rotating shaft that rotates about an axis, and a plurality of bearing pads spaced apart in the circumferential direction;
A support member that supports each of the bearing pads so as to be swingable by point contact from a side opposite to the side facing the thrust collar;
A bearing device, wherein a point contact position between the bearing pad and the support member is located radially inward from a center of a radial dimension of the bearing pad. The distance D from the inner peripheral edge of the bearing pad to the point contact position is relative to the radial dimension L of the bearing pad.
0.44L ≦ D ≦ 0.48L
The bearing device according to claim 1, wherein: The distance D from the inner peripheral edge of the bearing pad to the point contact position is relative to the radial dimension L of the bearing pad.
0.42L ≦ D ≦ 0.48L
The bearing device according to claim 1, wherein: A rotating shaft that has a thrust collar projecting radially outward and rotates about an axis;
A bearing device according to any one of claims 1 to 3,
A rotating machine characterized by comprising:

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