JPS6311531B2 - - Google Patents

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 a split fan-shaped bearing shaft arranged concentrically around a rotating shaft is swingable with 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 that is fixed to the rotating shaft 1 via a collar 2 and rotates together with the rotating shaft 1, and a runner 3 that is in sliding contact with the runner 3 and that is attached to the rotating shaft 1. Consists of a bearing shoe 4 arranged concentrically around the periphery, a support 8 that supports the bearing shoe 4 and is fixed with bolts or the like to a floor 7 at the bottom of a bearing oil tank 6 having an oil cooler 5. .
The bearing shoe 4 is swingably supported around a pivot 9 of the support 8 so as to be tiltable in all directions. In addition, in the same figure, 10 is a disc-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 normally used, and even if the runner 3 rotates slightly, the bearing shoe 4 tilts immediately, creating a wedge-shaped oil film between the bearing shoe 4 and the runner 3. It is designed to form a stable oil film. In so-called bidirectional rotating machines such as generator motors for pumped storage power plants that rotate in both directions, the bearing shoe 4 is generally supported at the center of its circumference, but this naturally reduces the ability to form an oil film. When the bearing shoe 4 is started or stopped, high-pressure oil is forcibly supplied to the sliding surface of the bearing shoe 4 to form an oil film to prevent damage to the sliding surface due to metal contact.

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 If the inner radius up to the inner diameter M of the bearing shoe 4 is R ₁ and the outer radius up to the outer diameter N is R ₂ , then R ₁ + R ₂ /2 is the center position). However, in this case, the bearing shoe 4 is tilted too much toward the outer diameter side, and as shown in the oil film pressure distribution curve K shown by the dotted line in the figure, the oil film on the inner diameter M side of the bearing shoe 4 becomes thinner, and the oil film pressure is higher on the inner diameter M side. It's summery. On the other hand, if the support point P is extremely shifted toward the outer diameter N side of the bearing shoe 4 as shown in FIG. 4, the outer diameter N of the bearing shoe 4 will be The oil film on the side becomes extremely thin, and the oil film pressure becomes higher on the outer diameter N side.

Among these, in the case of FIG. 3 mentioned above, the support point P of the bearing shoe 4, the angle θ, the inner radius R ₁ , the outer radius R ₂ ,
Radius Rs of support point P, area S ₁ on the inner diameter side, area S ₂ on the outer diameter side, radial length B, and support point P from the inner diameter side
The explanation will be as follows with reference to FIG. 5, which shows the length Bs, etc. The radius Rs to the support point P, the area S ₁ on the inner diameter side, the area S ₂ on the outer diameter side, and the ratio of the area S ₁ on the inner diameter side to the area S ₂ on the outer diameter side are respectively as follows: Rs = 1/2 (R ₁ + R ₂ ) ……(1) S ₁ = πθ/360 (R ² _s − R ² ₁ ) ……(2) S ₂ = πθ/360 (R ² ₂ − R ² _s ) ……(3) S ₂ /S ₁ = {R ² / ₂ - 1/4 (R ₁ + R ₂ ) ² } / {1/4 (R ₁
+R ₂ ) ² −R ² / ₁ } = 3R ² / ₂ −2R ₂ R ₁ −R ² / ₁ /R ² / ₂ −2R ₂
R ₁ −3R ² / ₁ ...(4) However, using a 300MVA class water turbine generator as an example, the inner radius of bearing shoe 4 is calculated by equation (4) R ₁ = 60
cm, outer radius R ₂ = 160 cm, and calculate: S ₂ /S ₁ = 3×160 ² −2×160×60−60 ² /160 ² +2×16
0 x 60 - 3 x 60 ² = 1.59, and since the area S ₂ on the outside diameter side of the bearing shoe 4 is extremely large, 1.59 times the area S ₁ on the inside diameter side, the bearing shoe 4 tilts toward the outside diameter side. . It is desirable for the bearing shoe 4 to tilt in the circumferential direction and generate a wedge-shaped oil film, but it is desirable not to tilt in the radial direction, and as mentioned above, if it tilts too much in the radial direction, the ability to generate an oil film will be reduced. There was a risk that a sufficient oil film would not be formed and the bearings would be damaged.

[Purpose of the invention]

The present invention has been made in view of the above points,
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]

That is, the present invention includes: a runner that is fixed to a rotating shaft via a collar and rotates together with the rotating shaft; a fan-shaped bearing shoe that is in sliding contact with the runner and is arranged concentrically around the rotating shaft; located between this bearing shoe and the bottom of the bearing oil tank,
In a thrust bearing device in which the bearing shoe is swingably supported around the pivot of the support body, the radius of the support point supported by the pivot of the bearing shoe is Rs, and the radius of the support point supported by the pivot of the bearing shoe is Rs. The inner radius is R ₁ , the outer radius is R ₂ , and the angle is θ
In this case, the radius Rs of the support point is (0.52R ₂ +
0.48R ₁ ) and 4/3・(R ³ / ₂ − R ³ / ₁ ) / (R ² / ₂ − R ² / ₁ )・180sin
(θ/2)/πθ. This allows the bearing shoe to be supported at a support point with reduced radial inclination.

We investigated the thrust bearing of a 300MVA class water turbine generator to find out where in the radial direction of the bearing shoe the fulcrum (support point) should be placed in order to reduce the inclination of the bearing shoe. The study results are shown in Figure 6.
This is the performance calculation result of a bearing shoe with an inner radius R ₁ of 60 cm, an outer radius R ₂ of 160 cm, and _an angle θ of 22 degrees. Taking the ratio of the direction length B, that is, the radial fulcrum position ratio Bs/B, and taking the maximum oil film temperature and minimum oil film thickness between the bearing shoe and the runner on the vertical axis, the radial fulcrum position ratio Bs The relationship between /B, maximum oil film temperature, and minimum oil film thickness is shown. As is clear from the maximum oil film temperature curve X and minimum oil film thickness curve Y based on the radial support position ratio Bs/B shown in the same figure, the minimum oil film thickness is reached when the radial support position ratio Bs/B is around 0.54. is the maximum, and the maximum oil film temperature is the 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 becomes 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 film temperature is increased. Regarding these, we further investigated the case where the radial support point position ratio Bs/B in FIG. 5 was changed. First, find the radius Rs of the support point where the inner diameter side area S ₁ and the outer diameter side area S ₂ are equal. Since it is sufficient to set S ₁ = S ₂ in equations (2) and (3), In this case, the radial fulcrum position ratio Bs/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 considerably smaller than those when the radial support position ratio Bs/B is 0.54. The maximum oil film temperature becomes higher. Next, when calculating the fulcrum of the center of gravity of the bearing shoe 4, the radius Rs of the center of gravity of the bearing shoe 4 is calculated.
is Rs=4/3・^R3 / ₂ ^−R3 / ₁ / ^R2 / ₂ − ^R2 / ₁・sin(θ
/2)/(2πθ/360) = 116.9 (cm) ...(6) From this, the radial fulcrum position ratio Bs/B is found to be 0.569, but in this case as well, the radial fulcrum position ratio Bs/B The minimum oil film thickness is lower than that of 0.54.

From these, the optimal support position in the radial direction of the bearing shoe in terms of bearing performance is the dimensional center position as shown in equation (1), the geometric area center position as shown in equation (5), and the optimal support position in the radial direction as shown in equation (6). Unlike the geometric center of gravity position, it is based on the hydrodynamic center of gravity position of the oil film, and although it varies depending on the load, circumferential speed and dimensions of the bearing shoe, it is roughly the same as equation (1) and equation (6). It has become clear that the radial support point position ratio Bs/B should be larger than 0.52. The radius Rs of the support point supported by the pivot of the bearing shoe that satisfies the condition that the radial support point position ratio Bs/B is Bs/B>0.52 is
Since Rs>(0.52R ₂ +0.48R ₁ ), in the present invention, the radius of the support point supported by the pivot of the bearing shoe is Rs, the inner radius of the bearing shoe is R ₁ , the outer radius is R ₂ ,
When the angle is θ, the radius Rs of the support point is larger than (0.52R ₂ + 0.48R ₁ ) and 4/3・(R ³ / ₂ − R ³ / ₁ ) / (R ² / ₂ − R ^2/1 )・_180sin
(θ/2)/πθ. 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 in the conventional system are given the same reference numerals, and therefore their explanations will be omitted. In this embodiment, the radius of the support point P supported by the pivot 9 of the bearing shoe 4 is Rs, the inner radius of the bearing shoe 4 is _R1 , and the outer radius is
R ₂ , the radius of the support point P is Rs when the angle is θ
is larger than (0.52R ₂ + 0.48R ₁ ) and 4/3・(R ³ / ₂ − ^{R 3} / ₁ ) / (R ² / ₂ − R ² / ₁ )・180 sin (θ/2
)/πθ. By doing this, the bearing shoe 4 is supported at a support point with reduced radial inclination, and the thrust bearing is capable of increasing the ability to generate oil film on the sliding surface between the bearing shoe 4 and the runner. You can get the equipment.

In other words, 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 from the center between the inner radius R ₁ and the outer radius R ₂ of the bearing shoe 4, that is, (1)
(B ₁ > B ₂ ) and (6)
It was set to be on the inner diameter side of the geometric center of gravity of the equation. By doing this, the radial fulcrum position ratio Bs/B, which is the ratio between the difference Bs between the radius Rs and the inner radius _R1 of the support point P of the bearing shoe 4 and the radial length B of the bearing shoe 4, is The minimum film thickness between the bearing shoe 4 and the runner 3 is large, and the maximum oil film temperature is small. In other words, the bearing shoe 4 is supported with a reduced radial inclination, and 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.
In addition, the bearing performance can be improved and the rotating electric machine can be operated safely.

[Effects of the Invention] As described above, the present invention enables the bearing shoe to be supported while reducing its radial inclination, and evens out the oil film generated on the sliding surface between the bearing shoe and the runner. Thus, 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 the drawing]

Fig. 1 is a longitudinal side view of a conventional thrust bearing device, Fig. 2 is a longitudinal side view of the area around the bearing shoe of the conventional thrust bearing device, and Fig. 3 is a longitudinal side view of the area around the bearing shoe of the conventional thrust bearing device. An explanatory diagram showing the state of oil film formation. Fig. 4 is an explanatory diagram showing the state of oil film formation between the bearing shoe and runner in another example of a conventional thrust bearing device. Fig. 5 shows the dimensions of the bearing shoe of the thrust bearing device. An explanatory diagram showing the symbols, FIG. 6 is a characteristic diagram showing 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, and FIG. 7 is one of the thrust bearing devices of the present invention. A partially enlarged view of the bearing shoe showing the support of the bearing shoe in the embodiment, FIG.
FIG. 9 is a plan view of the bearing shoe seen from direction A in the figure, and is an explanatory diagram showing the state of oil film formation between the bearing shoe and the runner in one embodiment of the thrust bearing device of the present invention. 1... Rotating shaft, 2... Collar, 3... Runner, 4... Bearing shoe, 6... Bearing oil tank, 7...
Bottom (floor) of the bearing oil tank, 8...Support, 9...Pivot, P...Support point.

Claims (1)

[Scope of Claims] 1. A runner that is fixed to a rotating shaft via a collar and rotates together with the rotating shaft, and a fan that is in sliding contact with the runner and arranged concentrically around the rotating shaft. a bearing shoe, and a support body disposed between the bearing shoe and the bottom of a bearing oil tank and having a pivot, the bearing shoe being swingably supported about the pivot of the support body. In a thrust bearing device, the radius of the support point supported by the pivot of the bearing shoe is Rs, the inner radius of the bearing shoe is R ₁ , and the outer radius is
R ₂ , the radius of the support point, where the angle is θ
Rs is larger than (0.52R ₂ + 0.48R ₁ ) and 4/3・(R ₂ ³ −R ₁ ³ )/(R ₂ ² −R ₁ ² )・180sin(θ/2)/πθ
A thrust bearing device characterized by being smaller.