JP6818668B2 - Tilting pad journal bearing and centrifugal compressor using it - Google Patents

Description

The present invention relates to a tilting pad journal bearing and a centrifugal compressor using the same.

In a high-speed rotating machine such as a centrifugal compressor, for example, a tilting pad journal bearing as shown in Non-Patent Document 1 is used. This tilting pad journal bearing has a plurality of pads arranged on the outer peripheral side of the rotating shaft and provided so as to be swingable. By forming an oil film between the inner peripheral surfaces of the plurality of pads (sliding portion), the radial load of the rotating shaft is borne while preventing contact between the rotating shaft and the pads. ..

In such a tilting pad journal bearing, the oil film temperature rises due to shear heat generation in the oil film. In particular, in a high-speed rotating machine such as a centrifugal compressor, the speed of the shaft surface (hereinafter referred to as "peripheral speed") is high and the temperature rise is large, which may cause damage to the bearing. In order to avoid this, some have a structure in which a flow path for cooling the pad is provided in the pad (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-109269

Japan Tribology Society, Tribology Handbook, Yokendo (2001), p53-57

A structure in which a flow path is provided in the pad for cooling, such as the tilting pad bearing described in Patent Document 1, has a problem that it is difficult to process.

An object of the present invention is a highly reliable tilt that has a simple structure, is easy to process, can effectively cool the bearing pad, and can keep the bearing temperature low even under high peripheral speed conditions. To provide ting pad journal bearings.

The tilting pad journal bearing of the present invention has a plurality of pads arranged on the outer peripheral side of the rotating shaft, a cylindrical housing that supports the pads so that they can swing, and a housing having a gap between the rotating shafts. The pad is provided with a sealing portion provided at the axial end portion of the housing, and the inner wall portion of the housing is arranged such that a convex portion having a lubrication hole faces the recess. , Arranged to supply lubricating oil towards the recess.

According to the present invention, it is possible to provide a highly reliable tilting pad journal bearing capable of keeping the bearing temperature low even under the condition that the peripheral speed is high and the oil film generates a lot of heat.

It is the schematic sectional drawing which shows the tilting pad journal bearing of this invention. It is a partial cross-sectional view which shows the detailed structure of the tilting pad journal bearing of Example 1. FIG. It is an exploded perspective view which shows the bearing pad 2a and the convex part 3 of FIG. It is a partial cross-sectional view which shows the modification of FIG. It is a partial cross-sectional view which shows the detailed structure of the tilting pad journal bearing of Example 2. FIG. It is an exploded perspective view which shows the bearing pad 2a and the convex part 3 of FIG. It is a partial cross-sectional view which shows the detailed structure of the tilting pad journal bearing of Example 3. FIG. It is an exploded perspective view which shows the bearing pad 2a and the convex part 3 of FIG. It is a top view which shows the example which provided the edge part on the upper surface part of the convex part. It is a top view which shows the example which provided the edge part on the upper surface part of the convex part. It is a top view which shows the example which provided the edge part on the upper surface part of the convex part.

Hereinafter, embodiments of the tilting pad journal bearing according to the present invention will be described.

(1) The tilting pad journal bearing has a plurality of pads arranged on the outer peripheral side of the rotating shaft, a cylindrical housing that supports the pads so that they can swing, and a gap between the rotating shafts. A seal portion provided at the axial end of the housing is provided, the pad has a concave portion, and a convex portion having an oil supply hole is arranged on the inner wall portion of the housing so as to face the concave portion. Is arranged to supply lubricating oil toward the recess.

With such a configuration, the lubricating oil supplied from the oil supply holes is ejected toward the recesses (part of the outer peripheral surface) of the opposing pads. This flow can effectively cool the outer peripheral surface of the pad. The bearing temperature can be lowered even under high peripheral speed conditions.

(2) In the tilting pad journal bearing, an edge portion is provided on at least one of the concave portion and the convex portion, and the main flow of lubricating oil in the gap between the concave portion and the convex portion is the rotation direction of the rotation axis. It is desirable that it functions as a flow path resistance so as to be.

(3) In the tilting pad journal bearing, it is desirable that the edge portion is provided at an upstream portion in the rotation direction of the rotation shaft at at least one of the concave portion and the convex portion.

(4) In the tilting pad journal bearing, it is desirable that the edge portion is provided at the end portion of at least one of the concave portion and the convex portion in the direction of the center line of the rotation axis.

(5) In the tilting pad journal bearing, it is desirable that the sliding surface of the pad has a notch portion due to a recess.

(6) In the tilting pad journal bearing, it is desirable that the downstream end of the convex portion projects to the downstream side of the downstream end of the pad.

(7) In the tilting pad journal bearing, it is desirable that the central axis of the oil supply hole is configured to intersect the facing surface of the recess substantially perpendicularly.

(8) The tilting pad journal bearing can be applied to a centrifugal compressor.

Hereinafter, examples according to the present invention will be described with reference to the drawings.

FIG. 1 shows the overall structure of a tilting pad journal bearing.

As shown in this figure, the tilting pad journal bearing 100 has a configuration in which five bearing pads 2a, 2b, 2c, 2d, and 2e (plurality of bearing pads) are arranged around the rotating shaft 1 (outer peripheral side). Have. A pivot 4 having a curvature is attached to the back surface of each bearing pad 2a, 2b, 2c, 2d, and 2e. Each pivot 4 is in point, line or surface contact with the bearing housing 5 (also simply referred to as the "housing"). As a result, the bearing pads 2a, 2b, 2c, 2d, and 2e are supported by the bearing housing 5 via the pivot 4. The pivot 4 may be provided on the inner wall portion of the bearing housing 5 and may have a structure in which the bearing pads 2a, 2b, 2c, 2d, and 2e are supported by points, lines, or surfaces. The bearing pad is also simply referred to as a "pad".

The bearing housing 5 is provided with a housing outer peripheral groove 50 for flowing the lubricating oil flowing from the oil tank 110 through the main oil supply pipe 130 along the circumferential direction of the bearing housing 5. A pump 120 is provided in the main oil supply pipe 130 so as to send lubricating oil from the oil tank 110 to the bearing housing 5.

Recessions 7 are provided in the bearing pads 2a, 2b, 2c, 2d, and 2e. A convex portion 3 is provided on the inner wall portion of the bearing housing 5 facing the concave portion 7. The bearing housing 5 is provided with a lubrication hole 8 for distributing lubricating oil from the outer peripheral groove 50 of the housing to the back surfaces of the bearing pads 2a, 2b, 2c, 2d, and 2e. The oil supply hole 8 also penetrates the convex portion 3. Spaces 10 are provided between the convex portion 3 and the bearing pads 2a, 2b, 2c, 2d, and 2e, respectively.

FIG. 2 is a partially enlarged view of the tilting pad journal bearing of FIG.

In FIG. 2, the tilting pad journal bearing has a plurality of bearing pads 2a and 2b arranged between the rotating shaft 1 and the bearing housing 5 (on the outer peripheral side of the rotating shaft 1). The pivot 4 attached to the bearing pads 2a and 2b is in contact with the inner wall portion of the bearing housing 5. As a result, the bearing pads 2a and 2b can swing. A seal portion (not shown) is provided at the axial end portion of the bearing housing 5. The inner peripheral surface of the seal portion is in a state of having a gap with the rotation shaft 1. The bearing pad 2a has a recess 7. The recess 7 has a shape in which a part of the bearing pad 2a is cut out.

On the other hand, a convex portion 3 is provided on the inner wall portion of the bearing housing 5. The convex portion 3 has a refueling hole 8. A part of the concave portion 7 and a facing surface 13 which is a part of the convex portion 3 face each other substantially in parallel. In other words, the gap between a part of the concave portion 7 and the facing surface 13 which is a part of the convex portion 3 fluctuates due to the swing of the bearing pad 2a, but the distance is almost the same in all the portions. An edge portion 17 is provided on the pivot 4 side of the recess 7. A narrow portion is formed between the edge portion 17 and the side surface portion of the convex portion 3. This narrow portion is narrower than the distance between the recess 7 and the facing surface 13.

FIG. 3 is an exploded perspective view showing the bearing pad 2a and the convex portion 3 of FIG.

As shown in FIG. 3, the recesses 7 of the bearing pad 2a have edge portions 27 at both ends in the center line direction of the rotating shaft 1. The convex portion 3 is inserted into the concave portion 7 so as to be sandwiched between the two edge portions 27. A narrow portion is also formed between the edge portion 27 and the convex portion 3.

In FIG. 2, the rotation shaft 1 rotates in the rotation direction indicated by the arrow R.

In the pad storage space formed by the rotating shaft 1, the bearing housing 5, and the seal (not shown) provided on the inner peripheral surface of the axial end of the bearing housing 5 while maintaining a gap with the rotating shaft 1. Lubricating oil is filled. The lubricating oil supplied to the pad storage space includes an annular oil supply flow path (housing outer peripheral groove 50 in FIG. 1) formed on the outer peripheral side of the bearing housing 5 and an oil supply hole 8 provided inside the convex portion 3. It is designed to eject toward the recess 7 via the. The supplied lubricating oil flows in the direction of the arrow Y because the narrow portion becomes a flow path resistance.

The rotating shaft 1 is lifted by the pressure of the lubricating oil (oil film) between the rotating shaft 1 and the inner peripheral surface of the bearing pad 2a, and is supported without directly contacting the bearing pad 2a. As the rotating shaft 1 rotates in the direction of the arrow R, the lubricating oil between the rotating shaft 1 and the inner peripheral surface of the bearing pad 2a flows in the direction of the arrow X. Further, as the rotation shaft 1 rotates, a shear stress is generated inside the oil film, and as a result, heat is generated (shear heat generation). The lubricating oil in the space 10 formed between the convex portion 3 and each bearing pad 2b induces a spiral flow as shown by the arrow Z by the movement of the rotating shaft 1.

As shown in FIG. 2, when the lubricating oil moves toward the narrow portion, the flow bends. In other words, a bent portion is formed on the upstream side of the narrow portion. Therefore, this bent portion also becomes a flow path resistance of the lubricating oil.

Next, the action and effect of this embodiment will be described.

In the configuration shown in FIG. 2, the lubricating oil, which is the cooling medium, is ejected toward the recess 7 through the oil supply hole 8 and collides with the recess 7, as shown by the arrow Y. As a result, the bearing pad 2a is cooled. Since the lubricating oil becomes a collision jet, it has a high heat transfer coefficient and enables effective cooling.

Further, bent portions (narrow portions) are provided on three sides (upstream portion and side portions) around the gap between the recess 7 of the bearing pad 2a and the facing surface 13. Therefore, the high-temperature lubricating oil staying in the pad storage space is difficult to be mixed in the gap. Therefore, the lubricating oil ejected from the refueling hole 8 can cool the recess 7 of the bearing pad 2a at a low temperature without rising so much from the temperature when it is discharged from the external refueling device (see FIG. 1). it can. As a result, the bearing temperature can be kept low even under the condition of high peripheral speed, and a highly reliable bearing can be provided. Further, when this bearing is applied to a centrifugal compressor, the rotation speed can be increased, so that a high-pressure centrifugal compressor can be realized.

FIG. 4 shows a modified example of FIG.

The difference from FIG. 2 in FIG. 4 is that the central axis (dashed line) of the oil supply hole 8 of the convex portion 3 is configured to intersect the facing surface of the concave portion 7 substantially perpendicularly. As a result, the heat transfer coefficient of the collision jet of the lubricating oil is further increased. As a result, cooling of the bearing pad 2a is promoted. Here, "substantially vertical" is defined based on a position where the swinging bearing pad 2a is substantially stable while the rotating shaft 1 is rotating.

This embodiment will be described with reference to FIGS. 5 and 6. In this embodiment, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

FIG. 5 is a partial cross-sectional view showing a detailed structure of the tilting pad journal bearing of the second embodiment.

FIG. 6 is an exploded perspective view showing the bearing pad 2a and the convex portion 3 of FIG.

The difference from FIG. 2 in FIG. 5 is that the recess 7 of the bearing pad 2a extends to the sliding surface 9 of the bearing pad 2a.

As shown in FIG. 6, a part of the sliding surface 9 is cut out. In other words, the recess 7 of the bearing pad 2a and the sliding surface 9 where the bearing pad 2a faces the rotating shaft 1 intersect. Here, the notched portion of the sliding surface 9 is a "notched portion" due to the recess 7.

In FIG. 5, the high temperature lubricating oil (arrow X) flowing out from the oil film between the rotating shaft 1 and the inner peripheral surface of the bearing pad 2a is lubricated at a lower temperature than in the case of FIG. It becomes easy to mix with oil (arrow Y). This has the effect of reducing the oil film inlet temperature of the bearing pad 2b on the downstream side.

By reducing the oil film inlet temperature in this way, it is possible to reduce the oil film temperature of the bearing pad 2a, and the bearing temperature can be kept low even under high peripheral speed conditions, so that a highly reliable bearing can be obtained. Can be provided. Further, when this bearing is applied to a centrifugal compressor, the rotation speed can be increased, so that a high-pressure centrifugal compressor can be realized.

This embodiment will be described with reference to FIGS. 7 and 8. In this embodiment, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

FIG. 7 is a partial cross-sectional view showing a detailed structure of the tilting pad journal bearing of the third embodiment.

FIG. 8 is an exploded perspective view showing the bearing pad 2a and the convex portion 3 of FIG. 7.

The difference from FIG. 2 in FIG. 7 is that the downstream end (right end in the figure) of the convex portion 3 projects to the right of the downstream end (right end in the figure) of the bearing pad 2a, and the width of the space 10 is wide. Is the point that is narrowing. In other words, the rear end portion of the convex portion 3 (refueling means) extends downstream from the rear end portion of the bearing pad 2a.

As shown in FIG. 8, the shape of the bearing pad 2a is the same as that shown in FIG. On the other hand, in the convex portion 3, the facing surface 13 has the same shape as that shown in FIG. 3, and the highest portion is a flat portion.

As shown in FIG. 7, since the width of the space 10 is narrowed due to the overhang of the convex portion 3, the spiral flow (arrow Z) generated between the convex portion 3 and the bearing pad 2b becomes small. Therefore, it is possible to reduce the loss corresponding to the energy required to induce this spiral flow. Therefore, the efficiency of the rotating machine to which this bearing is applied can be improved.

As described above, the bearing temperature can be kept low even under the condition of high peripheral speed, and a highly reliable bearing can be provided. Further, when this bearing is applied to a centrifugal compressor, the rotation speed can be increased, so that a centrifugal compressor that generates high pressure can be realized.

In Examples 1 to 3, a configuration in which a narrow portion is formed between the edge portion 17 of the bearing pad 2a and the side surface portion of the convex portion 3 has been described, but the present invention is limited thereto. Instead, it may have a structure in which a narrow portion is formed between the edge portion 17 and the facing surface 13. In other words, the edge portion 17 may be arranged above the facing surface 13.

Hereinafter, a modified example in which an edge portion (convex portion) is provided on the upper surface portion (opposing surface 13) of the convex portion 3 will be described with reference to the drawings. In the following description, the left side in the drawing is the upstream side of the flow of lubricating oil generated by the rotation of the rotating shaft.

FIG. 9 shows an example in which an edge portion is provided on the upstream side.

In this figure, an edge portion 23 is provided on the upstream side of the facing surface 13 (upper surface portion) of the convex portion 3. As a result, a narrow portion is formed between the concave portion of the bearing pad facing each other (for example, the concave portion 7 in FIG. 8) and the edge portion 23.

FIG. 10 shows an example in which an edge portion parallel to the flow of the lubricating oil is provided.

In this figure, edge portions 23 are provided at both ends in the direction of the center line of the rotation axis on the facing surface 13 (upper surface portion) of the convex portion 3. As a result, a narrow portion is formed between the concave portion of the bearing pad facing each other (for example, the concave portion 7 in FIG. 8) and the edge portion 23.

FIG. 11 shows an example in which edges are provided at three ends except the downstream side.

In this figure, U-shaped edge portions 23 are provided on the upstream side of the facing surface 13 (upper surface portion) of the convex portion 3 and at both ends in the direction of the center line of the rotation axis. As a result, a narrow portion is formed between the concave portion of the bearing pad facing each other (for example, the concave portion 7 in FIG. 8) and the edge portion 23.

1: Rotating shaft, 2a, 2b, 2c, 2d, 2e: Bearing pad, 3: Convex part, 4: Pivot, 5: Bearing housing, 7: Concave, 8: Lubricant hole, 9: Sliding surface, 10: Space , 13: Facing surface, 17, 23, 27: Edge, 50: Housing outer groove, 100: Tilting pad journal bearing, 110: Oil tank, 120: Pump, 130: Main oil supply pipe, X: Lubricant flowing out from oil film Oil flow, Y: flow of lubricating oil flowing out of the lubrication hole, Z: spiral flow between pads.

Claims (7)

Multiple pads arranged on the outer peripheral side of the rotating shaft,
A cylindrical housing that supports the pad so that it can swing,
A seal portion provided at an axial end portion of the housing with a gap from the rotating shaft is provided.
The pad has a recess and
A convex portion having a refueling hole is arranged on the inner wall portion of the housing so as to face the concave portion.
The oil supply holes are arranged so as to supply lubricating oil toward the recesses .
A tilting pad journal bearing in which the sliding surface of the pad has a notch formed by the recess . Multiple pads arranged on the outer peripheral side of the rotating shaft,
A cylindrical housing that supports the pad so that it can swing,
A seal portion provided at the axial end portion of the housing with a gap from the rotating shaft is provided.
The pad has a recess and
A convex portion having a refueling hole is arranged on the inner wall portion of the housing so as to face the concave portion.
The oil supply holes are arranged so as to supply lubricating oil toward the recesses.
A tilting pad journal bearing in which the downstream end of the convex portion projects downstream of the downstream end of the pad. An edge portion is provided at least one of the concave portion and the convex portion.
The edge portion according to claim 1 or 2, wherein the edge portion functions as a flow path resistance so that the main flow of the lubricating oil in the gap between the concave portion and the convex portion is in the rotation direction of the rotation axis. Tilting pad journal bearing. The tilting pad journal bearing according to claim 3 , wherein the edge portion is provided at least one of the concave portion and the convex portion in the upstream portion in the rotation direction of the rotation shaft. The tilting pad journal bearing according to claim 3 , wherein the edge portion is provided at an end portion of the concave portion and at least one of the convex portions in the direction of the center line of the rotating shaft. The tilting pad journal bearing according to any one of claims 1 to 5 , wherein the central axis of the refueling hole is configured to intersect the facing surface of the recess substantially perpendicularly. A centrifugal compressor comprising the tilting pad journal bearing according to any one of claims 1 to 6 .

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