JPH07113422A - Tilting pad thrust bearing - Google Patents

Abstract

PURPOSE:To prevent flow of lubricating oil from deviating in radial direction by influence of centrifugal force accompanied rotation so as to solve the shortage of lubricating oil on the rear end side of a pad inner circumferential end, in a tilting pad thrust bearing. CONSTITUTION:An circumferential groove 5 whose one end is opened to a pad front end along the inner circumferential end of a pad sliding surface 1 and the other end is stopped at the front of a pad rear end, is formed so as to lead lubricating oil to the inner circumferential end of the pad sliding surface 1. It is thus possible to take lubricating oil in the groove 5 by rotation of a rotating disc plate, and improve performance for smoothly supplying lubricating oil to the rear end range of a pad inner circumferential end where lubricating oil is often shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilting pad thrust bearing suitable for a high speed rotating machine such as a steam turbine, a gas turbine, an axial flow / radial compressor or a rotating machine such as a water turbine or an air preheater. Is.

[0002]

2. Description of the Related Art FIG. 3 shows a state of a pad arrangement of a conventional general tilting pad thrust bearing. In this thrust bearing, fan-shaped pads, which are obtained by dividing a disk into equal angles, are arranged concentrically. FIG. 4 shows one of them taken out, FIG. 5 is a sectional view taken along line Y-Y of FIG. 4, and FIG. 6 is a rear view of FIG. As can be seen from these, each pad is composed of a back metal 12 made of steel or the like in which a bearing alloy such as white metal is casted on the surface 11 and a pivot 13 on the back surface. The pivot 13 is arranged in contact with the bearing support plate 14. To be done. Since the pivot 13 has a spherical shape, the bearing pad can be tilted on the bearing support plate 14. In the conventional thrust bearing configured as described above, the lubricating oil is drawn by the rotation of the thrust disc surface into the slight gap formed between the thrust disc (thrust collar) attached to the rotating shaft (not shown). The mechanism of supporting the load of the shaft with low friction is generated by preventing the contact between the shaft and the bearing by generating the oil film pressure by the damming effect of the sandwiching gap due to the inclination of the bearing pad. Thus, in order to prevent the contact between the rotating disk surface and the bearing, it is necessary to generate an oil film pressure on the bearing pad. For that purpose, it is necessary to spread the lubricating oil over the entire sliding surface of the bearing pad (without chipping), a sufficient supply of lubricating oil, an appropriate inclination, and a smooth sliding surface are required.

By the way, as shown in FIG. 7, the flow of the lubricating oil in the bearing pad has a component based on the centrifugal force in addition to the component directed in the circumferential direction dragged by the surface of the rotating thrust disk, so that it is slightly It is deflected toward the outer periphery of the pad and flows through the portion A in FIG. Therefore, a part of the lubricating oil that has flowed in from the front end of the pad flows out from the outer peripheral end before reaching the rear end of the pad, and there is a region B where the lubricating oil is insufficient near the rear end side of the inner peripheral end of the pad. Occur. As a result, the effective oil film pressure generation area is reduced, and damage such as seizure or wear of the bearing is likely to occur mainly in the area where the lubricating oil is insufficient. As a result, the load capacity of the bearing becomes relatively small, and there is a problem that a bearing having an unnecessarily large area must be adopted.

[0004]

As described above, in the tilting pad thrust bearing, the flow of the lubricating oil is deflected in the radial direction due to the influence of the centrifugal force caused by the rotation.
There is a problem that a region of insufficient lubricating oil is likely to occur on the rear end side of the inner peripheral end as shown by B in FIG. SUMMARY OF THE INVENTION The present invention provides a tilting pad thrust bearing capable of improving the distribution of lubricating oil to a region on the rear end side of the pad inner peripheral end where the lubricating oil is apt to be insufficient, in order to solve the above conventional problems. Is what you are trying to do.

[0005]

Therefore, according to the present invention, in a tilting pad thrust bearing for supporting a thrust (axial direction) force of a rotary shaft, one end of the pad is provided along an inner peripheral end of a bearing pad sliding surface. A circumferential groove is provided which opens at the front end and stops at the other end before the rear end of the pad, and this is a means for solving the problem.

[0006]

According to the present invention, the lubricating oil can be guided to the inner peripheral edge of the pad sliding surface along the inner peripheral edge of the pad sliding surface.
By providing a circumferential groove, one end of which opens at the front end of the pad and the other end of which stops before the rear end of the pad, lubricating oil can be drawn into this groove by rotation of the rotating disc (thrust collar). Therefore, it is possible to improve the spreadability of the lubricating oil to the region on the rear end side of the inner peripheral end of the pad where the lubricating oil tends to be insufficient.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments of the drawings. FIGS. 1 and 2 are a front view and a sectional view showing a sliding surface of a bearing pad as an embodiment of the present invention. In FIG.
Reference numeral 1 denotes a sliding surface of the bearing pad, and the bearing pad is arranged with the rotating direction of the rotating disk (thrust collar) as N. Further, the sliding surface 1 of the pad is provided with a circumferential groove 5 having one end opening to the front end of the pad along the inner peripheral end and the other end stopping before the rear end of the pad. The circumferential groove 5 is formed as a groove having a uniform depth in the circumferential direction as shown in FIG. However, the same effect can be obtained by using an inclined groove whose depth gradually decreases from the opening at the front end of the pad to the dead end near the rear end of the pad. In the bearing pad configured as described above, the rotation of the rotating disc (thrust collar) causes the lubricating oil to be drawn in from the portion open at the front end of the pad, and the lubricating oil dragged in the groove in the rotational direction The pressure rises up to the dead end nearby. Therefore, the circumferential groove can be filled with the lubricating oil and can overflow into the surroundings, so that the lubricating oil can be easily spread to the region on the rear end side of the inner peripheral end of the pad where the lubricating oil is apt to be insufficient.

[0008]

As described above in detail, according to the present invention, it is possible to improve the distribution of the lubricating oil to the region where the lubricating oil is insufficient, which tends to occur near the inner peripheral rear end of the thrust bearing pad.
As a result, it is possible to prevent bearing damage such as seizure and abrasion that occurs mainly in this portion. Further, since the thrust bearing load capacity, which has been low in the past due to the occurrence of these damages, can be increased, a tilting pad thrust bearing having a high oil film rigidity can be realized.
Further, it has an excellent effect that it becomes possible to adopt a thrust bearing having a smaller size than the conventional one.

[Brief description of drawings]

FIG. 1 is a plan view showing a surface shape of a tilting pad thrust bearing according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line X-X in FIG.

FIG. 3 is a plan view showing an arrangement row of fan pads of a general tilting pad thrust bearing.

FIG. 4 is a plan view showing a surface shape of a conventional tilting pad thrust bearing.

5 is a cross-sectional view taken along line YY of FIG.

FIG. 6 is a rear view of FIG.

FIG. 7 is an explanatory diagram showing how a lubricating oil flows on the surface of a conventional fan-shaped pad.

[Explanation of symbols]

 1 Bearing pad sliding surface 2 Back metal 3 Pivot 4 Bearing support plate 5 Circumferential groove

Claims (1)

[Claims] 1. A tilting pad thrust bearing that supports a thrust (axial direction) force of a rotating shaft, one end of which is open at a front end of the pad and the other end is at the rear of the pad along an inner peripheral end of a bearing pad sliding surface. A tilting pad thrust bearing, characterized in that it is provided with a circumferential groove that stops before the end.