JPS58134221A - Oil film control device for thrust bearing - Google Patents

Abstract

PURPOSE:To prevent damages of a thrust bearing and a thrust collar due to the mingling of alien matter in lubricating oil by ensuring the thickness of oil film more than the diameter the alien matter. CONSTITUTION:The lubrication oil flowing inside a branch pipe 30 is introduced into a high pressure oil port 20 of a thrust bearing 6 via a pressure control valve 32 and a high pressure oil pipe 22 after pressurized by a pump 31. An output signal from an oil-film thickness detector 23 arranged in an oil groove 3c of a thrust plate 3 in the thrust bearing 6 and a signal from a pressure detector 34 are inputted into a pressure controller 33, which controls a pressure regulator valve 32 for maintaining a gap between a thrust plate 3 and a thrust collar 4a, that is, an oil film thickness ho between them constantly at a fixed value.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] 1. The present invention relates to a thrust bearing used in large-scale, high-speed turbomachinery such as a turbine generator. The present invention relates to an oil film control device for a thrust bearing that automatically controls the oil film thickness of the thrust bearing to improve durability and lubrication performance.

[Technical background of the invention]

- Fig. 1 shows an example of a thrust bearing used in large, high-speed turbomachines such as turbine generators.

The figure shows an example of a tapered land type thrust bearing, in which a thrust plate 3 is held in a bearing casing 2 housed in a bearing outer ring 1 in contact with a casing or a bearing stand, and the thrust between this thrust plate 3 and a rotating shaft 4 is By forming an oil film 5 by the wedge action of lubricating oil between the collars 4 and 4, the thrust force of the turbomachine is taken care of.

As shown in FIGS. 2 and 3, the thrust plate 6 is a steel plate or a steel plate (base plate) 3a" to which a bearing metal 3b such as white metal is welded, and its surface has oil grooves 3c provided radially. It is divided into a plurality of land parts.

In addition, each land is composed of a tapered part 3d and a flat part 3 with a large gap on the inlet side along the rotational direction U of the thrust collar 41 in order to generate a wedge oil film.

The supply of lubricating oil to the thrust bearing 6 having such a configuration is performed by a lubricating oil system illustrated in FIG. 4.

In the figure, the lubricating oil sucked up by the main pump 8 from the oil tank 7 is passed through the pressure regulating valve 9 and the oil cooler 10 to the thrust bearing 6 and journal bearing that support the rotating shaft of the steam turbine T and the generator G. 11, and after lubricating the inside of the bearing, returns to the oil tank 7 through a return pipe 12.

□・The temperature of the oil coming out of the oil cooler 10 is measured by the temperature detector 1.
By controlling the cooling water valve 14 using this detection signal, the temperature of the lubricating oil supplied to each bearing is maintained within a predetermined range.

Further, the pressure of the lubricating oil is regulated by a pressure regulating valve 91 controlled by the pressure detector 15.

In addition, in FIG. 4, 16 indicates a filter, and 17 indicates a lubricating oil purifier system.

[Problems with background technology]

In the thrust bearing equipped with the bearing lubricating oil system described above, the thickness of the oil film 5 between the thrust plate 3 and the thrust collar 41 changes due to changes in the operating conditions of the turbomachine, that is, changes in its rotation speed and thrust force. There is a risk of fluctuation and metal contact.

This metal contact between the thrust plate and the thrust collar is a problem that tends to occur when a wedge oil film is not yet sufficiently formed when starting or stopping a turbomachine. In practical terms, the more important problems of thrust bearings are the decrease in load capacity due to row wear, the seizure phenomenon, and the phenomenon of 11° high galling wear that occurs with high chromium rotor materials when starting and stopping. The major causes of this occurrence are foreign matter jamming in the high circumferential speed range, where the amount of heat generated is greater than in the low circumferential speed range, and overload conditions due to thrust force fluctuations.

Therefore, in order to solve this problem, it is necessary to ensure that the oil film thickness is greater than the diameter of the foreign particles mixed in the lubricating oil even after mechanical removal using filters etc. in all operating ranges. , the prior art tower could not satisfy this requirement.

[Purpose of the invention]

The present invention has been made with attention to the above points, and an object of the present invention is to provide an oil film control device for a thrust bearing that can prevent damage to a thrust plate and thrust collar due to metal contact or mixed foreign matter, and can reduce bearing loss. This is the purpose.

[Summary of the invention]

The oil film control device for a thrust bearing of the present invention opens a high-pressure oil plate on the thrust plate toward the thrust collar, and uses the output of an oil film thickness detector that detects the thickness of the oil film between the thrust plate and the thrust collar. Based on this, the pressure controller controls the pressure of the lubricating oil led from the high-pressure lubricating oil system to the high-pressure oil port, and is configured to ensure a desired oil film thickness over the entire operating range.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to FIGS. 5 to 7.

In these figures, the same members as in FIGS. 1 to 4 are given the same reference numerals.

Figures 5 and 6 show examples of the configuration of the thrust bearing section in the present invention, in which the thrust plate 3 is constructed by welding a bearing metal 3b to a pace brake (3m), and the surface thereof is a radial oil groove 3C. In order to generate a wedge oil film, each land is divided into a plurality of land parts by a tapered part 3d and a flat part 3 with a large inlet gap along the rotational direction U of the thrust collar 41. The structure is similar to that shown in FIGS. 1 to 3.

In FIG. 6, h and h8 indicate the oil film thickness on the outlet side and inlet side of the tapered portion 3d, respectively.

A high pressure oil port 20 is opened in each end portion.

These high-pressure oil ports are connected to a high-pressure lubricating oil system, which will be described later, via a communication hole 2-1 and a high-pressure oil pipe 22.

In terms of the circumferential direction, the high pressure oil port 20 is desirably located near the boundary between the tapered part 3d and the flat part 3, where the highest oil film pressure occurs when the thrust collar 41 is rotating at a high circumferential speed U. In the radial direction, the optimum oil film pressure position is at or near the maximum oil film pressure position located outward (0.6 to 0.7) from the center line (0,5) of each land.

This is because these highest oil film pressure positions hardly change even in the low circumferential speed range, and the static pressure effect when stationary is also effective because the position is not extremely close to the outlet end.

A non-contact displacement meter (oil film thickness detector) 2 is installed in a part of the oil groove 3c.
6 is placed.

Reference numeral 24 indicates a lead wire that leads the force of the non-contact displacement meter 23 to a pressure controller to be described later.

FIG. 7 shows an example of the configuration of a lubricating oil system in the present invention.

In the figure, the constituent members 7 to 17 and their connection relationships are the same as in the example of FIG. 4, so detailed explanations will be omitted and the differences will be mainly described.

The lubricating oil sucked from the oil tank 7 by the main pump 8 has its oil pressure adjusted by the pressure regulating valve 9, and then goes to the oil cooler 1.
0 into the thrust bearing 6 and journal bearing 11 of the turbomachine G%T, a part of which is introduced into the branch pipe 60.
The flow is diverted to the high-pressure lubricating oil system through the

The lubricating oil flowing through the branch pipe 30 is pressurized to a predetermined pressure by the high-pressure pump 61, and then the high-pressure oil port 20 (fifth
Figure 6).

The pressure controller 33 inputs the J output signal from the non-contact displacement gauge 26 disposed in the oil groove 3c of the thrust bearing 6 and the signal from the pressure detector 34. , the distance between the thrust plate 3 and the thrust collar 41, and therefore the thickness of the oil film between them.

The pressure regulating valve 32 is controlled so that the pressure is always maintained at a predetermined value.

Next, the operation and effects of the apparatus of the present invention will be explained with reference to FIGS. 8 to 12.

FIG. 8 is an example of an operating diagram showing the generation status of thrust loads in a steam turbine to which the present invention is applied, where the horizontal axis T is time;
N is the turbine rotation speed, Q is the turbine output (load), and F is the thrust load to be started.

As is clear from this figure, the thrust load F increases as the starting rotation speed increases, and also increases as the turbine output Q increases even at the rated rotation speed.

FIG. 9 shows the oil film thickness as a function of the rotational speed change under a constant load. The horizontal axis N represents the rotational speed, and h· represents the oil film thickness.

Curve person is when high pressure oil is not activated, and B is when high pressure oil is activated.

Figure 10 shows the oil film thickness due to load changes at a constant rotation speed, the horizontal axis F shows the thrust load, and ho, A, and B are the 9th
Same as the figure.

These FIGS. 9 and 10 are for the case where the west pressure hydraulic pressure is constant, but when the hydraulic pressure P is changed, it changes as shown in FIG. 11.

In the figure, Po is the lowest limit pressure value, below which the effect on oil film thickness is not apparent.

This value P changes depending on the operating conditions of the thrust bearing.

Based on the above conditions, FIG. 12 shows changes in oil film thickness under the operating conditions shown in FIG. 8.

In the figure, curve C shows the case where the oil film thickness is controlled by the device of the present invention and high pressure oil is operated, and Fl and F indicate the operating period.

In this way, in the present invention, by detecting the oil film thickness, it is possible to eliminate unnecessary operation of high-pressure oil and prevent a reduction in the oil film thickness due to thrust load fluctuations even in a high circumferential speed range.

In addition, if the oil film thickness to be managed needs to be thin depending on the rotational speed, the minimum oil film thickness can be adjusted by changing the high pressure hydraulic oil using the pressure controller.

〔Effect of the invention〕

As described above, the present invention controls the oil film thickness of the thrust bearing using high-pressure hydraulic oil from a high-pressure boat installed in the bearing to ensure an oil film thickness that is greater than the diameter of foreign objects mixed in the lubricating oil. Therefore, it is possible to prevent damage to the thrust bearing and thrust collar due to foreign matter in the entire operating range.

Additionally, increasing the oil film thickness using high-pressure oil is also effective in reducing thrust bearing loss.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the structure of a tapered land type thrust bearing, Figure 2 is a plan view showing a conventional thrust plate,
FIG. 6 is a sectional view of a conventional thrust plate and thrust collar, FIG. 4 is a system diagram showing a conventional lubricating oil system, FIG. 5 is a plan view showing an embodiment of the thrust plate in the present invention, and FIG. 7 is a system diagram illustrating the lubricating oil system of the present invention, FIG. 8 is a graph explaining the thrust load generation of a turbomachine, and FIG. 9 is a cross-sectional view of the thrust play gate and thrust collar in the invention. Figures 1 to 11 are graphs showing changes in oil film thickness due to high-pressure hydraulic oil with respect to rotational speed, thrust load, and hydraulic oil pressure, respectively, and Figure 12 is a graph showing an example of operation of the apparatus of the present invention. 1...Bearing outer ring 2...Bearing casing 3...Thrust plate 31...
...Pace plate 6b ...Bearing metal 3c ...Oil groove 3d ...Tapered part 6e ...Flat part 4 ......・Rotating shaft 4a... Thrust collar 5... Oil film 6... Thrust bearing 7... Oil tank 8... ......Y presentation pump 9.32...Pressure regulating valve 10...Oil cooler 11...
......Journal bearing 12...Return piping 13...Temperature detector 14...Cooling water valve 15, 34.・・Pressure detector 16・・・・−・−・Filter 17・・・・・・・Lubricating oil purifier system 20・・・・
...... High pressure oil port 21 ...... Communication hole 30 ...... Branch pipe 31 ...... High pressure pump 36 ...... ...Pressure controller (7317)
Representative patent attorney Noriyuki Chika (one idiot) Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 T (/1r) N Crprn) F (KN )

Claims (1)

[Claims] 1. In a thrust bearing of a turbo machine, a high-pressure hole opened on the thrust collar side of a thrust plate, and an oil film thickness for detecting the oil film thickness between the thrust plate and the thrust collar. A thrust controller comprising a pressure controller that controls the pressure of the lubricating oil guided from the high-pressure lubricating oil system to the high-pressure oil port based on the output of the oil film thickness detector. Bearing oil film control device. 2. The oil film control device for a thrust bearing as set forth in claim 1, wherein the oil film thickness detector comprises a non-contact displacement meter and is disposed in an oil groove of the thrust plate. 3. An oil film control device for a thrust bearing as set forth in claim 1 or 2, characterized in that the high pressure oil boat has an opening at or near the highest oil film pressure position on the thrust plate.