JPS5830522A - Water-lubricated bearing device - Google Patents

Abstract

PURPOSE:To enable to maintain stable performance even when a bearing pad is deformed by swelling, by a method wherein a guide surface formed to be higher than an introducing surface for lubricating water and lower than or flush with a bearing surface is provided at the front edge of a bearing pad. CONSTITUTION:The guide surface 33 formed to be higher than the introducing surface 34 for lubricating water is provided at a front edge part of the bearing pad 3. Therefore, even when the pad 3 is irregularly deformed and the front edge part comes into contact with the bearing surface 31, the contact occurs only at the guide surface 33, and the introducing surface 34 is kept apart from the bearing surface 31, so that water is introduced effectively to and a sufficient amount of water is supplied to the bearing surface 31. In addition, when a slanted surface 35 connecting a front part of the introducing surface 34 and the end face of the pad 3 is worked, a rotating flow is introduced to the introducing surface 33 without being divided by the end face, so that cooling is accelerated by a large amount of lubricating water. Accordingly, stable performance can be maintained while controlling the bearing temperature at a lower value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to an underwater bearing device for a chamber-shaft Kablan water turbine, and more particularly to a water-lubricated bearing device that is effective in reducing deformation and loss of a bearing pad (resin material).

As a measure to improve the river environment, lubrication of water turbine main bearings is being switched from the conventional grease lubrication method to water lubrication.
In underwater bearing devices that use general resin materials, a method has been applied in which the resin pad is directly fixed to the bearing housing with screws or the like. However, since the bearings may be damaged due to loosening of the screws, a patent application filed in 1986-67 was developed to prevent this from occurring.
7 etc. have been proposed. In this structure, the bearing pad material is supported by an elastic body, so swelling deformation in the circumferential direction is absorbed by the elastic body, which solves the problem of protruding in the radial direction and hugging the rotating shaft as when screwed.

However, since the base material of resin materials is mixed with cloth pieces that easily absorb water, there is a possibility of irregular deformation, and even if circumferential deformation can be absorbed by elastic support, distortion etc. If this occurs, the leading and trailing edges of the bearing pad will come into contact with the main shaft as shown in FIG. For example, if this phenomenon occurs at the inlet in the direction of shaft rotation, the leading edge will rub against the shaft, exhibiting a kind of wiper effect, and obstructing the flow of lubricating water flowing into the bearing pad surface, resulting in poor water lubrication and water film breakage. This led to a significant performance decline, bearing overheating, and a burnout accident.

To explain this problem with reference to FIG. 1, the bearing pad material 3 is positioned on the inner surface of the bearing housing 2 with a key 4.
If swelling deformation (especially irregular shape) occurs in a structure in which the split end face part of the split end face is supported by an elastic body 5 such as a leaf spring, and the front and rear edges are operated with the front and rear edges in contact with the main shaft 1, which is the rotating shaft, the leading edge The part rotates with the rotation of the shaft and scrapes off most of the lubricating water that tries to enter the pad surface 31 like a wiper,
Only a very small amount of water can be introduced. When operated under such conditions, no noticeable trouble will occur under light load and low speed conditions, but when high loads are applied at high speeds, the bearing surface will not be able to secure the absolute amount of water necessary for lubrication, as shown in Figure 2. First, a water film breakage region A occurs on most of the bearing surface, and the load capacity due to the water film is rapidly reduced, and the cooling effect is also lost, resulting in a significant deterioration in performance. Note that FIG. 2B shows the area where a water film occurs. In addition, when a tapered surface 32 for promoting the third acceleration is provided as in a general bearing, the third
Although there is no noticeable scraping effect as shown in the figure, the contact area of the shaft only moves to the tapered surface 32, and although a slight increase in water volume can be expected, the amount of water is far from the amount required for lubricant cooling. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a water-lubricated bearing device that can maintain stable performance even if a bearing pad for an underwater bearing undergoes amorphous swelling and deformation.

A feature of the present invention is a water-lubricated bearing device in which a guide surface is disposed on the front line (or trailing edge) of the bearing pad and is higher than the lubricating water introduction surface and lower than or flush with the bearing surface.

An embodiment of the present invention will be described below with reference to FIG. In the figure, the components other than the bearing pad 3) are the same as in FIG. It has a guide surface 33 arranged at the front edge, and the guide surface 33
Water is effectively introduced at the introduction surface 34, which is in contact only with no contact, and a sufficient amount of water is supplied to the bearing surface 31.

In addition, when the inclined surface 35 connecting the front of the introduction surface and the pad end surface is machined, the rotating flow flows into the introduction surface 33 without being divided by the pad end surface, and cooling is promoted by a large amount of lubricating water, resulting in bearing temperature. It is possible to maintain stable performance by keeping it low. Furthermore, in the structure shown in Fig. 6, the guide surface 33 is arranged near the center of the pad width, so even if foreign matter or abrasion powder flows in, particles with a diameter larger than the water film thickness will be trapped by the wedge water film on the introduction surface. Due to the pressure flow, it is released outside the bearing as shown by the dotted line, which prevents galling and wear due to dirt, etc. Note that it is essential to provide a step higher than the guide surface 33Ifi introduction surface 34, and even if the guide surface 33Ifi is on the same surface as the bearing surface 31, the effects of the present invention can be fully exhibited. Further, for devices where it is difficult to arrange the inclined surface 35, effects can be expected even if this is eliminated. However, it should be avoided to place the guide surface 33 at a higher level than the bearing surface, as this may cause lubricant water to be scraped off on the guide surface, resulting in unstable performance.

Further, it goes without saying that the idea of the present invention is applied to the front edge and rear edge of the pad in a reversible rotating machine.

In terms of more detailed dimensions, the step dimension between the introduction surface and the guide surface must be at least larger than the bearing radius clearance, and for permanent use, it is desirable to set it to be larger than the diameter clearance.

FIG. 7 shows another embodiment of the present invention. When using clean water with no foreign substances in the lubricating water, two guide surfaces can be placed at the top and bottom of the pad inlet. Leakage is prevented, the amount of water flowing into the bearing surface is increased, and further performance improvement can be expected. In addition, in the case of a rectangular pad with a long bearing width due to the equipment structure, as shown in Figure 8,
By arranging multiple guides in the width direction, even if the following torsional deformations occur, each guide surface prevents contact between the introduction surface and the shaft, allowing a constant supply of water and improving performance.

According to the present invention, even if unstable deformation occurs in the bearing material, stable performance of the bearing can be maintained, and the effect is very significant.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main part showing the deformed state of a conventional bearing device, Figure 2 is a developed view of the bearing surface showing the state of water film rupture in Figure 1, and Figure 3 is the contact of the pad inlet of Figure 1. A schematic diagram showing the state, and FIG. 4 is a contact state diagram of the inlet taper portion of FIG. 1. Fifth
6 is a perspective view of the bearing pad shown in FIG. 5, and FIGS. 7 and 8 are other embodiments of the present invention. It is a perspective view of a bearing pad showing. DESCRIPTION OF SYMBOLS 1... Main shaft, 2... Bearing housing, 3... Bearing pad, 4... Positioning key, 5... Elastic body, 31
...Bearing surface, Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 3゜

Claims (1)

[Claims] 1. Rotation - In a bearing device that supports a rotating shaft by interposing a bearing pad between the shaft and the bearing housing, the bearing pad is divided into a plurality of parts in the circumferential direction, and the dividing surface of the bearing pad is divided into a plurality of parts in the circumferential direction. In between, there is a positioning key that protrudes inward from the inner circumferential surface of the housing, and an elastic body that presses the key side surface and the divided side surface of the bearing pad. A water-lubricated bearing device characterized in that a guide surface is arranged which has a high level difference and is lower than the bearing surface or at the most flush with the bearing surface. 2. The water-lubricated bearing device according to claim 1, wherein an inclined surface is formed between the divided side surface of the bearing pad and the introduction slope. 3. The water-lubricated bearing device according to claim 1, wherein the guide surface step of the bearing pad is formed to be larger than the bearing clearance dimension.