JP2009257445A - Tilting pad thrust bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tilting pad thrust bearing achieving enhancement of a load capacity while effectively avoiding a rise in the temperature of the bearing without enlarging the size of the bearing (more exactly, a pad), and also without increasing an offset rate of a pivot. <P>SOLUTION: The tilting pad thrust bearings 10A, 10B bear an axial thrust acting on a rotor 11 by sandwiching both faces of a thrust collar 13 fixed to the rotor 11 in a collar shape by a plurality of the pads 14 aligned in the circumferential direction in slidable contact with one another. A plurality of spiral grooves 20 to which lubrication oils are led are formed on sliding faces of the pads 14 with the thrust collar 13. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tilting pad thrust bearing applied to a steam turbine, a gas turbine, and the like.

  It is well known that tilting pad thrust bearings are generally used to support the thrust load (axial thrust) of a rotor (rotating shaft) that is a high-speed rotating body such as a steam turbine or a gas turbine. (See Patent Document 1).

  This tilting pad thrust bearing has a plurality of pads supported by pivots, and when the thrust collar facing these pads rotates together with the rotor, the pad tilts at an appropriate angle, and the fluid (oil film) pressure is increased. The thrust load is supported by generating. In addition, a leveling plate (pad washer) built into the base ring is flexibly abutted on the back of the pads via the pivot to prevent one-sided contact, that is, the distribution of thrust load received by each pad is average. It has come to be.

Japanese Patent Laid-Open No. 7-310738

  By the way, the tilting pad thrust bearing described above is generally constructed as a thrust bearing using a so-called center pivot type pad that can be rotated forward and backward so that it can be used regardless of the direction of rotation. It has been.

  Therefore, when the thrust load increases and the bearing surface pressure increases, there is a problem that the bearing temperature rises. That is, as the bearing temperature rises, the viscosity of the lubricating oil decreases and the oil film becomes thin, which may cause metal contact between the pad and the thrust collar, and also causes deterioration of the lubricating oil.

  As these measures, it is conceivable to increase the size of the bearing (strictly, the pad) and increase the offset ratio of the pivot. However, in the former case, the bearing temperature decreases with an increase in the bearing area, but the bearing loss is proportional to the square of the peripheral speed and proportional to the size of the bearing (more precisely, the pad), and therefore increases significantly. There is. On the other hand, in the latter case, as shown in FIG. 6, the oil film thickness can be increased by an offset (wedge) effect and the charge amount of the lubricating oil is increased to lower the bearing temperature, but the bearing is weak against reverse rotation. There is a problem.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a tilting pad thrust bearing capable of increasing the load capacity while effectively avoiding an increase in bearing temperature without increasing the bearing (strictly, pad) size and increasing the pivot offset rate. Is to provide.

The tilting pad thrust bearing according to the present invention for solving the above problems is as follows:
In a tilting pad thrust bearing that supports axial thrust acting on the rotating shaft by sandwiching both surfaces of a thrust collar fixed to the rotating shaft in a bowl shape with a plurality of pads that are in sliding contact with each other in the circumferential direction.
A plurality of spiral grooves for guiding lubricating oil are formed on the sliding contact surface of the pad with the thrust collar.

Also,
The groove extends from the inner peripheral side to the outer peripheral side of the pad in the rotational direction of the thrust collar and has its tip closed.

Also,
The groove extends in the direction of rotation of the thrust collar from the outer peripheral side to the inner peripheral side of the pad and has its tip closed.

Also,
The groove is engraved in a herringbone shape with a groove extending in the rotation direction of the thrust collar from the inner peripheral side to the outer peripheral side of the pad and a groove extending in the rotation direction of the thrust collar from the outer peripheral side to the inner peripheral side of the pad. It is characterized by.

Also,
The pad is a center pivot type.

  According to the tilting pad thrust bearing according to the present invention, unlike the conventional pressure generation due to the wedge effect, the bias in the pressure distribution on the pad is reduced by the lubricating oil guided to the spiral groove. Therefore, the center pivot type also has a strong load capacity and a strong effect against reverse rotation. Further, since the lubricating oil passes through the groove, the cooling effect is great and the bearing temperature can be reduced. In other words, it is possible to increase the load capacity while effectively avoiding an increase in bearing temperature without increasing the size of the bearing (strictly, the pad) and increasing the offset rate of the pivot.

  Hereinafter, a tilting pad thrust bearing according to the present invention will be described in detail with reference to the accompanying drawings.

  1 is a surface view of a single pad in a tilting pad thrust bearing showing Embodiment 1 of the present invention, FIG. 2 is an overall perspective view of the tilting pad thrust bearing, and FIG. 3 is an assembled state diagram of the tilting pad thrust bearing. is there.

  As shown in FIG. 3, the tilting pad thrust bearings 10A and 10B in the present embodiment are installed via support plates 12A and 12B in a bearing stand (not shown) of a rotor (rotating shaft) 11 in a steam turbine, a gas turbine, or the like. Then, the thrust collar 13 fixed to the rotor 11 in a bowl shape is sandwiched by a plurality of pads 14 that are in sliding contact with each other in the circumferential direction to support the axial thrust (thrust load) acting on the rotor 11. ing.

  A leveling plate (pad washer) 16 incorporated in a housing-like base ring 15 is in contact with the back surface of the pad 14 via a pivot 17 in a flexible manner. The pivot 17 is positioned at the center of the pad 14 to support the pad 14, and the distribution of the thrust load received by each pad 14 is averaged. In FIG. 3, 18A and 18B are oil seals.

  In addition, as shown in FIG. 2, the pads 14 are arranged in the circumferential direction in the illustrated example by interposing an oil supply nozzle 19 between adjacent pads, and the fan-shaped surface (thrust collar 13 and The white metal 14a is welded with a predetermined thickness. In FIG. 2, 19a is a lubricating oil inlet to which lubricating oil from a lubricating oil supply source (not shown) is supplied, and 19b is a lubricating oil outlet.

  Further, as shown in FIG. 1, the surface of the pad 14 (strictly, the white metal 14a) extends in the rotational direction of the thrust collar 13 (in the direction of the arrow in FIG. 1) from the inner peripheral side of the pad 14 to the outer peripheral side. At the same time, a plurality (seven in the illustrated example) of spiral grooves 20 whose tips are blocked are formed. The lubricating oil discharged from the lubricating oil outlet 19 b of the oil supply nozzle 19 is guided to the grooves 20 through the inner peripheral surface and the side surface of the pad 14. In addition, the length of each groove 20 is set to a length that leaves an approximately 1/3 region (no groove is formed) on the outer peripheral side of the pad 14 surface.

  With this configuration, as the thrust collar 13 rotates, in the tilting pad thrust bearings 10A and 10B, the lubricating oil outlet 19b of the oil supply nozzle 19 is formed on the surface of the pad 14 (strictly, the white metal 14a). In addition, the lubricating oil is supplied to the grooves 20 through the inner peripheral surface and the side surface of the pad 14.

  Then, the lubricating oil guided to the grooves 20 from the inner peripheral side of the pad 14 generates a pressure due to a dead end on the way. Further, since pressure is generated at the outermost diameter portion of each groove 20, the position of the pivot 17 is provided outside the center portion of the pad width. Further, the center of the pad 17 in the circumferential direction of the pad 14 is a center (center pivot type).

  Unlike the conventional pressure generation by the wedge effect, the bias in the pressure distribution on the pad 14 is reduced by the lubricating oil guided to the spiral grooves 20 in this way. Therefore, the center pivot type also has a strong load capacity and a strong effect against reverse rotation. Further, since the lubricating oil passes through each groove 20, the cooling effect is great and the bearing temperature can be reduced.

  In other words, it is possible to increase the load capacity while effectively avoiding an increase in the bearing temperature without increasing the size of the bearing (strictly speaking, the pad 14) and increasing the offset rate of the pivot.

  FIG. 4 is a surface view of a single pad in a tilting pad thrust bearing showing Embodiment 2 of the present invention.

  This is because the spiral groove 20 in the first embodiment extends from the inner peripheral side of the pad 14 to the outer peripheral side in the rotational direction of the thrust collar 13, and the thrust collar 13 of the pad 14 extends from the outer peripheral side to the inner peripheral side. It is the example changed so that it might extend in the rotation direction. In this case, the position of the pivot 17 is provided inside the center portion of the pad width.

  According to this, as the thrust collar 13 rotates, the lubricating oil is guided into the respective grooves 20 from the outer peripheral side of the pad 14 toward the inner peripheral side, and the same operations and effects as in the first embodiment are obtained.

  FIG. 5 is a surface view of a single pad in a tilting pad thrust bearing showing Embodiment 3 of the present invention.

  This is because the spiral groove 20 in the first and second embodiments is merged, the groove 20A extending in the rotation direction of the thrust collar 13 from the inner peripheral side of the pad 14 to the outer peripheral side, and the inner periphery from the outer peripheral side of the pad 14 This is an example of forming a herringbone shape with a groove 20B extending in the rotational direction of the thrust collar 13 to the side. In this case, the pivot 17 is provided at the center of the pad width.

  According to this, along with the rotation of the thrust collar 13, the lubricating oil is guided into the respective grooves 20A from the inner peripheral side of the pad 14 toward the outer peripheral side, and into the respective grooves 20B from the outer peripheral side of the pad 14. Lubricating oil is guided toward the circumferential side, and a synergistic effect between Example 1 and Example 2 can be expected.

  In addition, the present invention is not limited to the above embodiments, and it goes without saying that various changes such as a change in the shape and dimensions of the pad 14 are possible.

It is a surface figure of the pad simple substance in the tilting pad thrust bearing which shows Example 1 of the present invention. It is a whole perspective view of a tilting pad thrust bearing. It is an assembly state diagram of a tilting pad thrust bearing. It is a surface view of the pad simple substance in the tilting pad thrust bearing which shows Example 2 of this invention. It is a surface view of the pad simple substance in the tilting pad thrust bearing which shows Example 3 of this invention. It is a graph which shows the offset ratio of the pivot in a pad, the bearing temperature, and the relationship of an oil film.

Explanation of symbols

10A, 10B Tilting pad thrust bearing 11 Rotor 12A, 12B support plate in steam turbine, gas turbine, etc. 13 Thrust collar 14 Pad 14a White metal 15 Base ring 16 Leveling plate (pad washer)
17 Pivot 18A, 18B Oil seal 19 Oil supply nozzle 19a Lubricating oil inlet 19b Lubricating oil outlet 20, 20A, 20B Spiral groove

Claims (5)

In a tilting pad thrust bearing that supports axial thrust acting on the rotating shaft by sandwiching both surfaces of a thrust collar fixed to the rotating shaft in a bowl shape with a plurality of pads that are in sliding contact with each other in the circumferential direction.
A tilting pad thrust bearing characterized in that a plurality of spiral grooves for guiding lubricating oil are provided on a sliding contact surface of the pad with a thrust collar.   2. The tilting pad thrust bearing according to claim 1, wherein the groove extends from the inner peripheral side to the outer peripheral side of the pad in the rotation direction of the thrust collar and is closed at a tip end thereof.   2. The tilting pad thrust bearing according to claim 1, wherein the groove extends from the outer peripheral side of the pad to the inner peripheral side in the rotation direction of the thrust collar and is closed at a tip end thereof.   The tilting pad thrust bearing according to claim 1, wherein the groove is carved in a herringbone shape with the groove according to claim 2 and the groove according to claim 3.   5. The tilting pad thrust bearing according to claim 1, 2, 3, or 4, wherein the pad is a center pivot type.

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