JPS60116915A - Thrust bearing device - Google Patents

Abstract

PURPOSE:To increase an ability to form an oil film on a sliding surface between a bearing shoe and a runner, by a method wherein the bearing shoe is positioned so that it can be supported through reduction of inclination in the direction of radius. CONSTITUTION:Provided a radius supported by a retainer member 10 of a bearing shoe 4 is RS, the inner radius of the bearing shoe 4 is R1, the outer radius thereof is R2, and an angle is theta, the radius R4 supported by the retainer member 10 is formed such that it is longer than (0.52R2+0.48R1) and is shorter than 4/3.(R2<3>-R1<3>)/(R2<2>-R1<2>).180sin(theta/2)/pitheta. This causes the bearing shoe 4 to be supported at a fulcrum P where inclination in the direction of radius is reduced, and enables improvement of an ability to form an oil film on a sliding surface between the bearing shoe 4 and a runner 3.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a thrust bearing device, and in particular to a thrust bearing device in which split fan-shaped bearing shoes arranged concentrically around a rotating shaft are swingably supported by a support. This relates to a supporting thrust bearing device.

[Background of the invention]

1 and 2 show conventional examples of thrust bearing devices used in water turbine generators and the like. As shown in the figure, the thrust bearing device includes a runner 3 fixed to the rotating shaft l via a collar 2, and a runner 3 that rotates together with the rotating shaft l.
a bearing shoe 4 in sliding contact with the bearing 3 and arranged concentrically around the rotation l14111;
The bearing oil tank 6 supports a bearing oil tank 6 and has an oil cooler 5.

The bearing shoe 4 has two pivots 9 projecting upward at a predetermined distance, and a support body 8 consisting of a leaf spring II having two pivots 9 projecting upward at a predetermined distance and a cylindrical or spherical support member 10 projecting downward. It is swingably supported by a leaf spring 11 and a support member 10 as a fulcrum so as to be able to tilt in any direction. In addition, in Figure 2, 1
2 is a disk-shaped support.

In a thrust bearing device configured in this way, the position of the support point of the bearing shoe 4 has a great influence on bearing performance. A so-called eccentric support system in which the runner 3 is slightly shifted in the rotational direction from the center in the circumferential direction is usually used, and even if the runner 3 rotates slightly, the bearing shoe 4 immediately tilts, creating a wedge-shaped oil film between the bearing shoe 4 and the runner 3. to form a stable oil film. So-called bidirectional rotating machines, such as generator motors for pumped storage power plants that rotate in both directions, are generally supported at the circumferential center of the bearing shoe 4, but this naturally reduces the ability to form an oil film. When starting or stopping, high-pressure oil is forcibly supplied to the sliding surface of the bearing shoe 4 to form a full oil film and prevent the sliding vJ.
This is to prevent damage caused by metal contact between surfaces.

On the other hand, regarding the radial support point of the bearing shoe 4, conventionally the radial center position of the bearing shoe 4 (in this case the bearing The total inner radius n up to the inner diameter M of the shoe 4,
, External R up to outer diameter N, +R2 If diameter tR2, '7- is the center position) is the support point (
It was supported as a fulcrum) P, but in this case, the bearing shoe 4
5. is too tilted toward the outer diameter side, as shown in the oil film pressure distribution curve shown by the dotted line in the figure. The oil film on the inner diameter M side of the bearing shoe 4 is thinner, and the oil film pressure is higher on the inner diameter M side. Support point P for this? Bearing shoe 4 as shown in FIG.
If the bearing shoe 4 is shifted extremely toward the outside diameter N side, the oil film on the outside diameter N side of the bearing shoe 4 becomes extremely thin, contrary to the case shown in FIG. 3 above.
The oil film pressure is higher on the outer diameter N side.

Among these, for the case shown in FIG. 3 above, the bearing shoe 4 has a supporting point P, an angle θ, an inner radius R3, an outer radius 2, a radius Rs of the supporting point P, an inner diameter smaller diameter side area S8, and an outer diameter side area. 82% radial length B Figure 5 shows the length Bs from the inner diameter side of the machining to the support point P, etc.? For reference, the explanation is as follows. Radius Rs to support point P, area on inner diameter side 81%
The ratio of the area S2 on the outside diameter side and the area S on the inside diameter side and the surface aS2 on the outside diameter side is different, but - for example, a 300MVA class water turbine generator? For example, in equation (4), the inner radius of bearing 4 is 81 = 60C.
By substituting rnx outer radius Rt = 160 cmk and making a trial calculation, the area S2 on the outer diameter side of the bearing shoe 4 is extremely large at 1.59 times the area S1 on the inner diameter side, so the bearing shoe 4
is inclined toward the outer diameter side. Although it is desirable that the bearing shoe 4 be tilted in the circumferential direction to produce a wedge-shaped oil film,
It is desirable that it not be tilted in the radial direction; if it is too tilted in the radial direction as described above, the oil film generation force will be reduced and a sufficient oil film will not be generated, leading to the risk of damaging the bearing.

[Purpose of the invention]

The present invention has been made in view of the above points, and it is an object of the present invention to provide a thrust bearing device that can increase the ability to generate an oil film on the sliding surface between a bearing shoe and a runner.

[Summary of the invention]

In other words, does the present invention have a collar on the rotating shaft? A runner that is fixed through the runner and rotates together with the rotating shaft, a fan-shaped bearing shoe that is in sliding contact with the runner and arranged concentrically around the rotating shaft, and the bearing shoe and the bottom of the bearing oil tank. two pivots disposed between and projecting upward at a predetermined distance and a cylindrical or spherical support member projecting downward? In a thrust bearing device, the bearing shoe is swingably supported via the leaf spring and the pivot as a full fulcrum of the support member, and the bearing shoe is supported by the support member of the bearing shoe. radius kRs, inner radius of bearing shoe R1, outer diameter Ft, t
, when the angle is θ, the radius R supported by the support member
s'? (0.52R2) is characterized by being smaller than 0.52R2, so that the bearing shoe is supported at a support point where the radial inclination is reduced.

In order to reduce the inclination of the bearing shoe, the fulcrum (support point) should be set at any position in the radial direction (+-1300
We investigated the thrust bearings of MVA class water turbine generators. The study results are shown in Figure 6, which is the performance calculation result of a bearing shoe with an inner radius of 60 cm * outer radius of 160 crn, and an angle of 22 degrees. The ratio to the radial length Bs of the bearing shoe, that is, the radial fulcrum position ratio Bs/Bk, and the maximum oil film temperature and minimum oil film thickness between the bearing shoe and the runner on the vertical axis, The relationship between the fulcrum position ratio B s / B and the maximum oil film temperature and minimum oil film thickness is shown. The radial fulcrum position ratio B s /
Maximum oil film temperature curve X and minimum oil film thickness curve Y according to B
As is clear from , the radial fulcrum position ratio B s /
When B is around 0.54, the minimum oil film thickness is maximum and the maximum oil film temperature is minimum. This is because the inclination of the bearing shoe in the radial direction becomes smaller and the oil film on the sliding surface between the bearing shoe and the runner is uniform and large from the inner diameter side to the outer diameter side. In comparison, at the radial support point position ratio Bs/B of 0.50, that is, at the conventional support point, the minimum oil film thickness is considerably reduced and the maximum oil temperature is high. Regarding these, we further investigated the case where the radial direction/fulcrum position ratio Bs/Bk in FIG. 5 was changed.

First, find the support point radius ask where the inner diameter surface area S and the outer diameter surface area S2 are equal. Since it is sufficient to set S, = S in equations (2) and (3), the following is obtained, and the radial direction in this case Fulcrum position ratio B s / B
is 0.608, but as is clear from Figure 6, the maximum oil film temperature and minimum oil film thickness in this case are smaller than those when the radial support position ratio B s / B is 0.54. The maximum oil film temperature will be high.

Next, when the fulcrum of the center of gravity of the bearing shoe 4 is calculated, the radius Rs of the center of gravity of the bearing shoe is as follows, and from this, the radial fulcrum position ratio B s / B
The required value is 0.569, but in this case as well, the minimum oil film thickness is lower than that when the radial fulcrum position ratio Bs/B is 0.54.

From these, the optimal support position in the radial direction from the perspective of bearing performance of the bearing shoe is the dimensional center position as shown in equation (1), (
Unlike the geometric center of area position as shown in equation 5) and the geometric center of gravity position as shown in equation (6), it is based on the hydrodynamic center of gravity position of the oil film, and the bearing shoe load and circumferential speed are Although it differs depending on the dimensions, it generally exists between α) formula and (6) formula, and the radial fulcrum position ratio B s / B
? It has become clear that it is sufficient to make it larger than 0.52. This radial fulcrum position ratio B s / B is B
s/B > 0.520 The radius R of the support point supported by the support member of the bearing shoe that satisfies the condition R, s is Rs > (0,
52 几, +0.48R,) Therefore, in the present invention, the radius supported by the support member of the bearing shoe is '! 1-Rs, the inner radius *R of the bearing 7, the outer radius kR2, and the angle tθ, the radius supported by the support member Rg k (0,5
2R20.48L, smaller than N. By doing so, it is possible to obtain a thrust bearing device that can increase the ability to generate an oil film on the sliding surface between the bearing shoe and the runner.

[Embodiments of the invention]

The present invention will be explained below based on the illustrated embodiments. An embodiment of the present invention is shown in FIGS. 7-9.

Note that parts that are the same as those of the prior art are given the same reference numerals, and therefore their explanations will be omitted. In this embodiment, when the radius Rsk of the bearing shoe 4 supported by the support member lO, the inner radius kR1-outer radius kRz of the bearing shoe 4, and the angle θ, the support member lo
The radius Rs k (0,52FLz 10,
48R,) thicker. By doing this, the bearing shoe 4 is supported at the fulcrum P where the inclination in the radial direction is reduced, making it possible to increase the ability to generate an oil film on the sliding surface between the bearing shoe 4 and the runner 3. A thrust bearing device can be obtained.

That is, by calculating the hydrodynamic center of gravity position of the oil film, the position of the support point P of the bearing shoe 4 is determined based on the inner radius R of the bearing shoe 4,
and the center of the outer radius R2, that is, the outer diameter side (B, >332) than the position of equation (1), and the inner diameter side of the geometric center of gravity position of equation (6). By doing this, the difference B6 between the radius Rs of the support point P of the bearing shoe 4 and the inner radius R8 and the radial length B of the bearing shoe 4
The radial fulcrum position ratio B s /B, which is the ratio between the bearing shoe 4 and the runner 3, has a value such that the minimum film thickness between the bearing shoe 4 and the runner 3 is large and the maximum film temperature is small. In other words, the bearing shoe 4 is supported with a reduced inclination in the radial direction, so that the thickness of the oil film generated on the sliding surface with the runner 3 is uniform from the inner diameter M side to the outer diameter N side, and As a result, the bearing performance can be improved and the rotating electric machine can be operated safely.

〔Effect of the invention〕

As described above, the present invention enables the bearing shoe to be supported with its radial inclination reduced, thereby reducing the oil film generated on the sliding surface between the bearing shoe and the runner in the radial direction. uniform and increasing. You will be able to
It is possible to obtain a thrust bearing device that can increase the ability to generate an oil film on the sliding surface between the bearing shoe and the runner.

[Brief explanation of drawings]

Figure 1 is a vertical side view of a conventional thrust bearing device, Figure 2 is a vertical side view of the area around the bearing shoe of a conventional thrust bearing device, and Figure 3 is a vertical side view of a conventional thrust bearing device.
The figure is an explanatory diagram showing the entire state of oil film formation between the bearing shoe and runner of a conventional thrust bearing device, and Figure 4 shows the state of oil film formation between the bearing shoe and runner of another example of the conventional thrust bearing device. Fig. 5 is an explanatory drawing showing the dimension symbols of the bearing shoe of the thrust bearing device, and Fig. 6 shows the relationship between the radial support position of the bearing shoe of the thrust bearing device, the minimum oil film thickness, and the maximum oil film temperature. FIG. 7 is a partially enlarged view showing the support of the bearing shoe of an embodiment of the thrust bearing device of the present invention, FIG. 8 is a plan view of the bearing shoe seen from the input direction of FIG. 7, and FIG. 9 FIG. 2 is an explanatory diagram showing the state of oil film formation between a bearing shoe and a runner in an embodiment of the thrust bearing device of the present invention. l...rotation axis, 2...collar, 3...runner,
4...Bearing shoe, 6...Bearing oil tank, 7...Bottom (floor) of the bearing oil tank, 8...Support, 9...Pivot)
, 10... Support member, 11... Leaf spring, P... Support point. '$l Figure 茅 3 Prisoner 4 Hard No.

Claims (1)

[Scope of Claims] 1. A runner that is fixed to a rotating shaft through a collar and rotates together with the rotating shaft, and a sector-shaped runner that is in sliding contact with the runner and is arranged concentrically around the rotating shaft. A bearing shoe, two pivots disposed between the bearing shoe and the bottom of the bearing oil tank, projecting upwardly at a distance, and a cylindrical or spherical support member projecting downwardly? In the thrust bearing device, the bearing shoe is swingably supported via the leaf spring and the pivot (Th) as a fulcrum of the support member, wherein the bearing shoe is The radius supported by the support member? R8, the inner radius kR+s of the bearing shoe, the outer radius eat, and the angle θ, the radius supported by the support member Rsk(0,52Rz+0.
A thrust bearing device characterized by being thicker than 48Rt). 2. The thrust bearing device according to claim 1, wherein the second pivot is provided at a left-right symmetrical position opposite to the installation position of the support member.