JPH0547535U - Tilting pad type thrust bearing device - Google Patents

Abstract

(57) [Abstract] [Purpose] It is easy to design and manufacture, has a simple structure, has excellent durability, and can be used in a wide range of rotating machines from small rotating machines to large rotating machines. [Structure] On the stationary plate 2, a step portion 5 is formed on the stationary plate 2 on the exit side of the rotary plate 1 when the rotary plate 1 is rotated forward. The circumferential length from the stationary plate inlet end 2a to the stationary plate support center 3 during rotation is X _1, and the circumferential length from the support center 3 to the tip 5a of the descending step portion is X ₂ , and the descending step portion 5 If the circumferential length of X is X ₃ , X ₁
> X ₂ and X ₁ <(X ₂ + X ₃ ) are satisfied. The depth H of the descending step portion 5 is such that the descending step portion 5 does not form a bearing effective surface when the rotating plate 1 rotates forward, that is, it does not generate a membrane pressure, and forms a bearing effective surface when rotating in the reverse direction. It has been selected to generate a membrane pressure.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a tilting pad type thrust bearing device, and more particularly to a tilting pad type thrust bearing device for supporting a thrust load of a reversible rotating machine.

[0002]

[Prior Art]

 BACKGROUND ART A reversible rotating machine such as a pumped-turbine generator or an electric motor uses a thrust bearing device that supports a thrust load in both forward and reverse directions. Further, a pump machine or the like which does not have a mechanism for preventing reverse rotation may receive reverse force due to a fluid force and may reversely rotate. Therefore, a thrust bearing device that allows reversible rotation is required. As such a reversible rotation thrust bearing device, a reversible structure tilting pad type thrust bearing device, which has a high load capacity and is excellent in stability and assembly, is widely used.

First, the principle of the tilting pad type thrust bearing device will be briefly described. FIG. 5 shows the principle of a general tilting pad type thrust bearing. The rotary plate 1 is rotated in the direction of arrow A. A stationary plate 2 that supports the thrust load of the rotary plate 1 is supported at a support center 3. In this tilting pad type thrust bearing, when the position of the support center 3 is X ₄ / (X ₄ + X ₅ ) = 0.55 to 0.60 with respect to the rotary plate 1 rotating in the direction of arrow A, Sufficient membrane pressure is generated and the maximum load is obtained (“Bearing” Iwanami Zensho).

As described above, in the tilting pad type thrust bearing device having the above-described configuration, the support center position is optimal with respect to the rotation in the arrow A direction, and the maximum load is obtained. However, the support center position is not optimal for reverse rotation, and the maximum load cannot be obtained. Therefore, in the conventional tilting pad type thrust bearing device having a reversible structure, as shown in FIG. 6, the support center 3 is set to the center of the stationary plate 2 and the sliding surface of the stationary plate 2 is set to the minimum film thickness. It has a convex shape. The convex shape is machined into a convex shape in advance, or is formed by thermal deformation during operation, that is, deformation due to a temperature difference in the thickness direction. Due to such an appropriate degree of bilateral symmetry, sufficient film pressure is generated both in forward rotation A and in reverse rotation B (Proceedings of the Japan Society of Mechanical Engineers: Vol. 31, No. 231, page 1731 “Deformation of Michel thrust bearing About ”Hisashi Tahara).

In the conventional reversible structure tilting pad type thrust bearing device shown in FIG. 7, the lubricant temperature is directed toward the outlet side of the stationary plate 2 with the support center 3 as the center of the stationary plate 2. It utilizes the so-called “heat wedge effect” in which the membrane pressure rises and the membrane pressure is generated due to the decrease in density.

[0006]

[Problems to be solved by the device]

 However, in the conventional tilting pad type thrust bearing device having a reversible structure shown in FIG. 6, in addition to the problem that high precision machining is required when the bending is obtained by machining, There is also a problem that it is easy to flatten due to wear loss at the time of starting and stopping, and has poor durability. Further, when obtaining a curved surface by thermal deformation, sufficient experimental data and analysis are required, and there is a problem that a large amount of experiments must be carried out every time it is applied to a rotating machine having a different structure and size.

The conventional reversible structure tilting pad type thrust bearing device shown in FIG. 7 cannot generally be expected to generate sufficient pressure due to the thermal wedge effect. The problem is that it is practically nothing and its application range is very limited. Therefore, an object of the present invention is to provide a tilting pad type thrust bearing device for a reversible rotating machine, which is easy to design and manufacture, has a simple structure, has excellent durability, and has a wide range of application.

[0008]

[Means for Solving the Problems]

To achieve this object, the present invention relates to a tilting pad type thrust bearing device in which the thrust load of a rotating plate that can rotate in both forward and reverse directions is supported by a plurality of stationary plates via fluid lubricating oil. And a downward step portion that does not form a bearing effective surface during the forward rotation but forms a part of the bearing effective surface during the reverse rotation, on the outlet side in the forward rotation of the rotating plate. . In this configuration, the stationary plate has a length in the circumferential direction from the stationary plate inlet end to the supporting center of the stationary plate at the time of forward rotation as X _1, and the circumferential direction from the supporting center to the leading end of the descending step portion. When the length is X ₂ and the circumferential length of the descending step portion is X ₃ , it is desirable that X ₁ > X ₂ and X ₁ <(X ₂ + X ₃ ) are satisfied.

[0009]

[Action]

 During normal rotation of the rotary plate, the down step does not form a bearing effective surface, and the film pressure is not substantially generated in the down step. Therefore, the effective bearing surface of the stationary plate is substantially from the inlet side at the time of forward rotation to the front of the step portion. On the other hand, when the rotating plate rotates in the reverse direction, the step-down portion forms a part of the bearing effective surface due to the step effect, and the film pressure is also generated in the step-down portion. Therefore, at this time, the bearing surface of the stationary plate is substantially lowered and becomes the entire surface including the step portion. In this way, the descending step surface does not form the bearing effective surface during normal rotation, but forms the bearing effective surface during reverse rotation, so the relative positional relationship between the support center and the bearing effective surface reverses from that during normal rotation. It changes with time. Therefore, an eccentric support structure in which the support center is eccentric to the respective outlet sides during both forward and reverse rotations is possible.

[0010]

【Example】

An embodiment of a tilting pad type thrust bearing device for a reversible rotating machine according to the present invention will be described with reference to FIGS. 1 to 4 in which the same parts as those in FIGS. explain. In FIG. 1, the rotary plate 1 is rotatable in both forward and reverse directions, and each of the stationary plates 2 to 10 is supported at the support center 3, and the rotary plate 1 is stationary via the fluid lubrication film 4. Instruct by board 2. The stationary plate 2 is provided with a concave portion, that is, a descending step portion 5 on the outlet side of the rotary plate 1 indicated by an arrow A when the rotary plate 1 is normally rotated. Stationary plate 2, the circumferential length of the stationary plate inlet end 2a during the forward rotation to the stop plate support center 3 and X _1, the circumferential length to the tip 5a of the step portion falls from the support center 3 X ₂ and X ₃ is the circumferential length of the descending step portion 5, X ₁ > X ₂ and X ₁ <(X ₂ + X ₃ ) are satisfied. Specifically, the circumferential length X ₃ of the descending step portion 5 is approximately 20% to 30% of the total length of the stationary plate 2 in the circumferential direction, that is, X ₃ / (X ₁ + X ₂ + X ₃ ) = 0.2. ˜0.3 is preferable, and the position of the support center 3 is preferably X ₁ / (X ₁ + X ₂ ) = 0.55˜0.60.

The depth H of the descending step portion 5 does not constitute a bearing effective surface when the descending step portion 5 is in the forward rotation of the rotary plate 1, that is, does not generate a membrane pressure, and does not constitute the bearing effective surface in the reverse rotation. It is selected to generate the membrane pressure by a step effect. Specifically, the depth H of the descending step portion 5 is preferably 3 to several times the average lubricating film thickness.

Next, the operation of this embodiment will be described. When the rotary plate 1 is in the normal rotation A, the bearing effective surface is from the inlet end 2a to the tip 5a of the step portion, that is, (X ₁ + X ₂ ), as shown in FIG. 2, and X ₁ > X _Since it is ₂ , it becomes the eccentric support center and a sufficient lubricating film is formed. When the rotating plate 1 is in the reverse rotation B, the film pressure is generated in the descending step portion 5 by the step effect (dam effect) as shown in FIG. Therefore, the bearing effective surface in this case is the entire surface of the stationary plate 2, that is, the portion of (X ₁ + X ₂ + X ₃ ), and X ₁ <(X ₂ + X ₃ ). A sufficient lubricating film is formed. The magnitude of the film pressure generated in the descending step portion 5 depends on the step ratio (average film thickness / H).

FIG. 4 illustrates the step effect and shows a step bearing 6 and its pressure distribution 7. As a specific numerical example of this embodiment, X ₃ / (X ₁ + X ₂ + X ₃ ) = 0.3 and X ₁ / (X ₁ + X ₂ ) = 0.60. At this time, the eccentric support center position at the time of forward rotation is 0.60, and the pressure distribution 8 giving the maximum load capacity shown by the broken line in FIG. 2 occurs. The support center position during reverse rotation is (X ₂ + X ₃ ) / (X ₁ + X ₂ + X ₃ ) = 0.58. Therefore, the step ratio is analyzed as a parameter, and the depth H of the descending step portion 5 is determined so that the above value 0.58 is the optimum eccentric support position.

[0014]

[Effect of the device]

 As is apparent from the above description, according to the present invention, the stationary plate does not form the bearing effective surface at the forward rotation of the rotating plate but does not form the bearing effective surface at the forward rotation but a part of the bearing effective surface at the reverse rotation. Since it has a descending step, the relative positional relationship between the support center and the bearing effective surface can be changed between forward rotation and reverse rotation, and the support center is eccentric to the outlet side during both forward and reverse rotation. Structures are possible.

Therefore, since the tilting pad type thrust bearing device according to the present invention does not require the curved shape of the stationary plate and does not utilize the thermal wedge effect, it is easy to design and manufacture and has a simple structure. It has excellent durability and can be used for a wide range of rotating machines from small rotating machines to large rotating machines.

[Brief description of drawings]

FIG. 1A is a plan view showing a stationary plate of an embodiment of a tilting pad type thrust bearing device according to the present invention.
FIG. 1B is a sectional view taken along the line YY of FIG.

FIG. 2 is a cross-sectional view showing the operation of the above-described embodiment when the rotating plate is rotated normally.

FIG. 3 is a cross-sectional view showing the operation of the above embodiment when the rotating plate is rotated in the reverse direction.

FIG. 4 is a sectional view and a graph for explaining the step effect.

FIG. 5 is a cross-sectional view showing a conventional tilting pad type thrust bearing device.

FIG. 6 is a cross-sectional view showing a conventional tilting pad type thrust bearing device having a reversible structure.

FIG. 7 is a cross-sectional view showing another conventional tilting pad type thrust bearing device having a reversible structure.

[Explanation of symbols]

 1 Rotating plate 2 Stationary plate 3 Support center 5 Down step part A Forward rotation B Reverse rotation

Claims (2)

[Scope of utility model registration request] 1. A tilting pad type thrust bearing device for supporting a thrust load of a rotating plate rotatable in both forward and reverse directions by a plurality of stationary plates via fluid lubricating oil, wherein the stationary plate is a normal rotation of the rotating plate. A tilting pad type thrust bearing device having a descending step portion which does not form a bearing effective surface at the time of the forward rotation and forms a part of the bearing effective surface at the time of the reverse rotation on the outlet side of the. 2. The length of the stationary plate in the circumferential direction from the stationary plate inlet end at the time of the normal rotation to the support center of the stationary plate is X ₁ .
When the circumferential length from the support center to the tip of the descending step portion is X ₂ and the circumferential length of the descending step portion is X ₃ , X ₁ > X ₂ and X ₁ <(X ₂ +
X ₃ ) is satisfied, The tilting pad type thrust bearing device of Claim 1 characterized by the above-mentioned.